Issued  June  25, 1909. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF,  ANIMAL  INDUSTRY.— BULLETIN  112. 

y*T 

A.  D.  MELVIN,  CHIEF  OF  BUREAU. 


FHE  LOCO-WEED   DISEASE 
OF  THE  PLAINS. 


BY 


C.  DWIGHT  MARSH, 

Expert,  Poisonous-Plant  Investigations, 
Bureau  of  Plant  Industry. 


WASHINGTON: 

r,<>\ -\ -KNMI-NT    PRINTING    OFFICE. 

1909. 


Issued  June  25, 1909. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  -112. 

A.  D.  MELVIN,  CHIEF  OF  BUREAU. 


THE  LOCO-WEED  DISEASE 
OF  THE  PLAINS. 


BY 


C.  DWIGHT  MARSH, 

Expert,  Poisonous- Plant  Investigations, 
Bureau  of  Plant  Industry. 


WASHINGTON: 

GOVERNMENT    PRINTING   OFFICE. 
1909. 


THE  BUREAU  OF  ANIMAL  INDUSTRY. 

Chief:  A.  D.  MELVIN. 

Assistant  Chief:  A.  M.  FARRINGTON. 

Chief  Clerk:  CHARLES  C.  CARROLL. 

Biochemic  Division:  M.  DORSET,  chief;  JAMES  A.  EMERY,  assistant  chief. 

Dairy  Division:  B.  H.  RAWL,  chief. 

Inspection  Division:  RICE  P.  STEDDOM,  chief;  MORRIS  WOODEN,  R.  A.  RAMSAY, 
and  ALBERT  E.  BEHNKE,  associate  chiefs.  . 

Pathological  Division:  JOHN  R.  MOHLER,  chief;  HENRY  J.  WASHBURN,  assistant 
chief. 

Quarantine  Division:  RICHARD  W.  HICKMAN,  chief. 

Zoological  Division:  B.  H.  RANSOM,  chief. 

Experiment  Station:  E.  C.  SCHROEDER,  superintendent;  W.  E.  COTTON,  assistant. 

Animal  Husbandman:  GEORGE  M.  ROMMEL. 

Editor:  JAMES  M.  PICKENS. 


LETTER  OF  TRANSMITTAL. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY, 

Washington,  D.  C.,  January  16,  1909. 

SIR  :  I  have  the  honor  to  transmit  herewith,  for  publication  as  a 
bulletin  of  this  Bureau,  a  manuscript  entitled  "  The  Loco-Weed  Disease 
of  the  Plains/'  by  Dr.  C.  Dwight  Marsh,  expert,  of  the  Office  of  Poison- 
ous Plant  Investigations,  Bureau  of  Plant  Industry,  being  a  report 
of  field  investigations  carried  on  during  1905,  1906,  and  1907. 

Although  the  work  reported  in  this  paper  was  done  under  the 
supervision  of  the  Bureau  of  Plant  Industry,  it  has  been  considered 
desirable,  inasmuch  as  it  deals  largely  with  subjects  coming  within 
the  scope  of  the  Bureau  of  Animal  Industry,  such  as  the  symptoma- 
tology, pathology,  and  treatment  of  a  disease  of  animals,  to  have  it 
published  as  a  bulletin  of  the  latter  Bureau. 

For  many  years  the  so-called  loco  disease  has  been  a  cause  of  heavy 
loss  to  the  stockmen  of  the  West,  and  it  has  been  generally  attributed 
by  them  to  certain  plants  eaten  by  the  stock.  As  far  back  as  1886 
the  Bureau  of  Animal  Industry  investigated  the  subject,  and  an 
article  by  Dr.  M.  Stalker  in  the  Third  Annual  Report  of  the  Bureau 
has  up  to  the  present  time  remained  the  most  satisfactory  published 
description  of  the  disease.  While  Doctor  Stalker  in  that  report 
expressed  the  belief  that  the  loco  plant  "is  possessed  of  some  toxic 
property  that  has  a  specific  effect  on  the  nerve  centers,"  and  while 
these  plants  have  long  been  classed  as  poisonous  in  the  publications 
of  this  Department,  it  has  remained  for  Doctor  Marsh  in  the  work 
herein  reported  to  present  experimental  proof  that  the  plants  have 
a  poisonous  effect  and  really  cause  the  disease  and  to  suggest  a  line 
of  treatment,  and  for  Dr.  A.  C.  Crawford,  in  Bulletin  I'-".)  of  the 
Bureau  of  Plant  Industry,  to  discover  and  identify  barium  as  a 
poisonous  clement  in  the  plants. 

Respectfully,  A.  1).  MKLVIX, 

Chuf  of  Jiureau. 

lion.  JAMES  WILSON, 

Secretary  of  Agriculture. 


LETTER  OF  SUBMITTAL 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  PLANT  INDUSTRY, 

Washington,  D.  C.,  July  10,  1908. 

SIR:  I  take  pleasure  in  handing  you  herewith,  for  publication  as 
a  bulletin  of  the  Bureau  of  Animal  Industry,  the  accompanying  manu- 
script presenting  a  technical  report  entitled  "The  Loco- Weed  Disease 
of  the  Plains,"  prepared  by  Dr.  C.  Dwight  Marsh,  expert,  working 
under  the  direction  of  Dr.  Rodney  H.  True,  Physiologist  in  Charge  of 
Poisonous-Plant  Investigations  in  the  Bureau  of  Plant  Industry. 

This  bulletin  presents  the  evidence  obtained  from  an  experimental 
field  study  of  the  relation  of  the  so-called  "loco  weeds"  to  the  losses 
frequently  attributed  to  the  eating  of  them  by  horses,  cattle,  and 
sheep.  The  plants  studied  are  those  characteristic  of  the  plains,  and 
work  has  been  carried  on  under  actual  field  and  corral  conditions. 
The  investigation  has  been  fully  successful  in  proving  the  suspected 
plants  to  be  the  cause  of  great  and  widely  scattered  stock  losses.  It 
has  made  possible  a  satisfactory  description  of  the  disease  and  fur- 
nishes a  basis  on  which  other  disorders,  now  confused  wTith  loco-weed 
disease,  but  of  different  origin,  may  be  distinguished  from  it.  It  has 
developed  a  method  of  successfully  treating  a  large  percentage  of 
loco  cases  when  such  occur  under  circumstances  making  the  frequent 
handling  of  the  animals  practicable. 

A  companion  bulletin,  dealing  with  the  technical  laboratory  studies 
carried  on  at  the  same  time  in  Washington  by  Dr.  A.  C.  Crawford, 
pharmacologist,  is  a  necessary  supplement  to  this  bulletin  for  any- 
one desiring  a  full  account  of  the  loco-weed  disease.  This  bulletin  is 
entitled  "Barium,  a  Cause  of  Loco- Weed  Poisoning,"  and  constitutes 
Bulletin  No.  129  of  the  series  of  this  Bureau. 

Respectfully, 

B.  T.  GALLOWAY, 

Chief  of  Bureau. 
Dr.  A.  D.  MELVIN, 

CJtief,  Bureau  of  Animal  Industry. 

4 


PREFACE. 


The  so-called  "loco-weed  disease"  of  horses,  sheep,  and  cattle  has 
been  a  source  of  most  serious  complaint  for  many  years,  especially 
from  such  stockmen  as  have  grazed  their  animals  on  the  Great  Plains 
east  of  the  Rocky  Mountains.  While  the  losses  have  varied  in  severity 
from  year  to  year,  they  have  reached  such  a  magnitude  as  to  make 
the  matter  one  of  national  concern.  On  account  of  both  the  eco- 
nomic importance  of  the  problem  and  of  its  intrinsic  scientific  inter- 
est numerous  investigations  approaching  the  subject  from  the  most 
varied  standpoints  have  been  undertaken.  As  a  net  result  there  has 
appeared  a  large  body  of  literature  marked  by  a  wide  diversity  in  the 
conclusions  reached.  This  discouraging  state  of  disagreement  pre- 
vailed among  the  reported  results  of  the  field  studies  on  the  subject 
prior  to  the  time  at  which  the  Office  of  Poisonous  Plant  Investigations 
undertook  its  campaign,  but  it  was  believed  that  by  laying  siege  to 
the  problem  in  a  more  thoroughgoing  and  persistent  way  than  any 
of  its  predecessors  had  been  in  a  position  to  do  it  might  still  be  able 
to  ascertain  the  essential  facts  of  the  loco  situation. 

Accordingly,  in  1905  a  field  station  was  established  at  Hugo,  Colo., 
in  cooperation  with  the  Colorado  Agricultural  Experiment  Station, 
which  furnished  the  animals  used,  and  experimental  feeding  work  on 
horses  and  cattle  was  begun.  The  state  of  opinion  both  among  prac- 
tical stockmen  and  among  scientists  had  made  clear  the  first  step  to 
be  taken.  Popular  opinion  had  long  pointed  to  the  eating  of  certain 
members  of  the  pea  family  (Leguminosae),  especially  Astragalus  mol- 
lissimus,  the  purple  loco  weed,  and  to  Aragattus  lamberti,  the  rattle- 
weed,  as  the  probable  cause  of  poisoning.  The  first  task  was  to  test 
the  accuracy  of  this  report.  Accordingly  feeding  experiments  under 
field  and  corral  conditions  on  plants  of  known  origin  were  undertaken 
at  Hugo,  and  parallel  laboratory  tests  were  carried  on  at  Washington. 
The  results  showed  clearly  that  loco  symptoms  were  produced  as  a 
result  of  loco-weed  feeding,  and  as  the  investigation  proceeded  the 
characteristics  of  this  chronic,  progressive  disease  were  thoroughly 
worked  out. 

The  disagreement  above  referred  to  arose  from  a  number  of  causes, 
not  least  of  which  was  the  kind  of  animal  upon  which  the  investi- 
gations had  been  carried  out.  Those  working  on  sheep  had  seen 
much  reason  to  regard  the  symptoms  observed  as  fully  accounted 
for  by  the  various  kinds  of  animal  parasites  with  which  this  animal 


6  PKEFACE. 

is  affected  in  regions  in  which  the  loco  disease  has  been  regarded  as 
prevalent.  Another  reason  for  disagreement  lay  in  the  fact  that  the 
characteristic  symptoms  of  the  loco-weed  disease  had  not  been  sharply 
presented  as  a  result  of  the  experimental  production  of  the  disease; 
hence  "loco"  has  been  a  general  term  covering  many  kinds  of  trouble 
of  a  more  or  less  chronic  type.  Indeed,  there  seems  to  be  good  reason 
for  believing  that  in  some  cases  starvation  has  been  called  "loco." 
Another  source  of  confusion  has  lain  in  the  fact  that  investigators 
taking  a  more  or  less  superficial  view  of  the  matter  had  seen  animals 
in  various  stages  of  the  disorder  and  had  not  gone  into  the  matter 
deeply  enough  to  correlate  the  different  phases  of  a  progressive  disease. 

The  second  stage  of  the  field  work  looked  forward  to  measures  of 
relief.  The  behavior  of  the  plants  concerned  was  looked  into  and 
methods  of  eradication  tried.  Contrary  to  frequently  expressed 
belief,  these  weeds  were  found  to  be  easy  of  extirpation  by  thoroughly 
digging  them  out.  Methods  of  meeting  the  trouble  from  the  stand- 
point of  the  animals  concerned  were  in  a  degree  worked  out. 

Laboratory  work  carried  on  at  Washington  seemed  to  show  that 
the  loco  plants  coUected  in  the  vicinity  of  the  Hugo  station — and 
doubtless  those  of  eastern  Colorado,  Nebraska,  and  Kansas — owe  their 
poisonous  character,  to  a  certain  degree,  to  the  presence  in  them  of 
barium  absorbed  from  the  soil.  For  a  fair  understanding  of  the  loco 
situation  both  the  bulletin  herewith  presented,  dealing  with  the  field 
phase  of  the  work,  and  the  companion  publication  on  "Barium,  a 
Cause  of  the  Loco-Weed  Disease,"  based  on  the  laboratory  work, 
must  necessarily  be  taken  into  account.  Unfortunately  the  nature 
of  these  conclusions  was  not  indicated  until  near  the  close  of  the 
work  for  the  season  of  1907,  so  that  the  work  in  the  direction  of  re- 
medial measures  gained  no  advantage  from  this  information.  Those 
measures  which  were  found  to  be  most  beneficial  are  shown,  however, 
by  the  light  from  the  laboratory  result,  to  be  weU  founded.  The 
field  work  has  been  carried  out  by  Dr.  C.  Dwight  Marsh,  expert,  and 
his  assistants,  the  laboratory  work  by  Dr.  A.  C.  Crawford,  pharma- 
cologist. 

The  present  work  by  Doctor  Marsh  consists  of  a  technical  report  on 
prolonged  field  feeding  investigations  in  connection  with  the  loco 
problem,  carried  out  at  Hugo  and  Woodland  Park,  Colo.,  and  Im- 
perial, Nebr.,  in  cooperation  with  the  Colorado  Agricultural  Ex- 
periment Station  and  the  Nebraska  Agricultural  Experiment  Station. 
Doctor  Marsh  has  here  succeeded  in  working  out  very  completely  and 
more  thoroughly  than  has  ever  been  done  heretofore  the  symptoma- 
tology of  the  true  loco  disease,  and  has  given  a  basis  on  which  to 
distinguish  the  trouble  known  as  loco,  properly  speaking,  from 
various  types  of  pseudo-loco  which  have  gone  under  this  name.  He 
has  also  described  the  plants  which  cause  the  trouble  and  outlined 
their  distribution. 


PREFACE.  7 

The  experiments  intended  to  secure  the  extermination  of  the 
plants  are  summarized,  the  conclusion  of  which  is  that  the  most 
practicable  way  of  disposing  of  the  plants  is  to  dig  them  out.  This 
can  be  done  on  land  which  is  taken  up  by  settlers,  and  will  relieve  a 
large  number  of  sufferers.  The  question  of  the  open  range,  in  so  far  as 
it  is  still  Government  property,  is  one  which  we  see  noway  of  handling 
except  by  Federal  appropriation. 

The  treatment  of  animals  is  also  outlined,  it  appearing  that  horses 
and  cattle  require  somewhat  different  handling.  Horses  are  helped 
by  daily  treatment  with  Fowler's  solution,  and  cattle  do  best  with 
slight  daily  doses  of  strychnin,  accompanied  with  laxative  feed  and 
occasional  doses  of  magnesium  sulphate.  Further  work  is  planned  on 
wholesale  antidoting  under  range  conditions. 

R.  H.  TRUE, 
Physiologist  in  Cliarge,  Poisonous-Plant  Investigations, 

Bureau  of  Plant  Industry. 


CONTENTS. 


Pago 

PART  I. — INTRODUCTION 15 

Historical  summary  and  review  of  literature. 15 

Symptoms  mentioned  in  literature 32 

Remedies  proposed 33 

Conclusions  from  literature „. 34 

Plants  known  as  loco  plants 36 

List  of  Bpccies 36 

Description  of  Aragallus  lambcrli 37 

Description  of  Astragalus  mollissimus 38 

Dispersal  of  Aragallus  lamberli  and  Astragalus  jnoU'i-ssimtis 3!) 

Relations  of  loco  plants  to  fertile  soil 40 

Experimental  work  limited  to  two  plants , 40 

PART  II.— EXPERIMENTAL  WORK. 42 

The  problem  to  be  solved 42 

Plan  of  work 43 

Location  of  experiment 43 

Preliminary  work 44 

Work  of  the  first  season 45 

Experiments  with  cattle 47 

Experiments  with  horses 49 

Cases  of  cattle  and  horses  not  subjects  of  experiment f>2 

Summary  of  first  season's  work 54 

Work  of  the  second  and  third  seasons 55 

Experiments  with  cattle 56 

Experiments  with  horses 02 

Experiments  with  sheep 06 

Discussion  of  sheep  experiments 09 

Experiment  at  Woodland  Park,  Colo 71 

Experiment  at  Imperial,  Ncbr 73 

Remedial  measures , 73 

Treatment  with  strychnin  in  1906 75 

Treatment  with  arsenic  in  1906 78 

Results  of  treatment  in  1906 81 

Treatment  of  cattle  in  1907 83 

Treatment  of  horses  in  1907 88 

Treatment  of  sheep  in  1907 90 

PART  III.  —RESULTS  AND  CONCLUSIONS 91 

Cause  of  the  disease 91 

Symptoms  of  loco  poisoning 92 

Pathological  lesions 95 

Examination  of  blood 95 

Walls  of  stomach 97 

Hemolymph  glands 97 

Nervous  system 97 

9 


10  CONTENTS. 

PART  III. — RESULTS  AND  CONCLUSIONS — Continued.  Page. 

Virulence  of  loco  poison 98 

Time  required  to  produce  poisoning 98 

Amount  of  loco  necessary  to  produce  poisoning 100 

Relative  importance  of  Astragalus  mollissimus  and  Aragallus  lamberti 101 

Susceptibility  of  different  breeds 102 

Age  susceptibility 102 

Effect  on  animals  other  than  horses,  cattle,  and  sheep 103 

Effect  on  man 104 

Losses  from  loco  poisoning 104 

Destruction  of  loco  weeds 105 

Insects  destroying  loco  plants 106 

Effect  of  dry  seasons 108 

Remedies , 108 

Treatment  of  cattle  in  1907 110 

Treatment  of  horses  in  1907 110 

General  results  of  treatment Ill 

Results  with  cattle Ill 

Results  with  horses Ill 

Permanency  of  loco  cures Ill 

Prevention  of  loco  poisoning 112 

Summary  of  work  on  remedies 112 

GENERAL  SUMMARY 113 

BIBLIOGRAPHY i 117 

INDEX  .  127 


ILLUSTRATIONS. 


PLATES.     . 

Page. 
PLATE  I.  White  loco,  or  rattle  weed  (Aragallus  lamberti).     Fig.  1. — Plant  in 

flower.     Fig.  2.— Plant  in  fruit 38 

II.  Purple  or  woolly  loco  (Astragalus  mollissimus) .     Fig.  1. — Flower 

and  fruit.     Fig.  2.— Habit  of  the  plant 38 

III.  Fig.  1. — Case  8,  July  19,  1905.  Just  before  the  locoed  condition 
was  particularly  evident.  Fig.  2. — Case  8,  August  3,  1905. 
When  animal  showed  typical  symptoms  of  loco  poisoning. 
Fig.  3. — Case  8,  August  23,  1905.  Emaciated  condition  of 
the  animal  and  typical  loco  attitude  of  lowered  head  and  braced 
legs.  Fig.  4. — Case  8,  August  23.  1905.  Loco  leaping  unneces- 
sarily high  in  going  over  a  rut  in  the  road.  Fig.  5. — Case  8, 
August  23,  1905.  Lifting  foot  unnecessarily  high  in  passing 
over  a  wire.  Fig.6. — Case  8,  August  27, 1905.  Animal  too  weak 

to  stand  unaided 50 

IV.  Fig.  1. — Case  18,  May  12, 1905.  A  mare  weakened  by  loco  poison- 
ing. Fig.  2.— Case  18,  June  27,  1905.  Advanced  condition  of 
loco  poisoning.  Fig.  3. — Case  19,  May  16,  1905.  Before  eating 
any  of  the  loco  weed.  Fig.  4. — Case  19,  August  31,  1905. 
Animal  eating  loco  at  a  time  when  it  has  lost  some  flesh,  but 
was  not  in  bad  condition.  Fig.  5. — Case  19,  October  15,  1905. 
Animal  in  a  very  much  reduced  and  emaciated  condition. 
Fig.6.— Case  19,  October  26, 1905.  Animal  just  before  its  death.  50 
V.  Fig.  1.— Case  524.  Peculiar  way  in  which  a  locoed  horse  uses  its 
mouth  in  attempting  to  eat.  Fig.  2. — Case  533.  How  a  locoed 
horse  will  rear  when  suddenly  startled.  Fig.  3. — Case  525. 
Peculiar  gait  which  a  badly  locoed  horse  exhibits.  Fig.  4. — 
Case  525.  Horse  rearing  when  suddenly  startled  by  a  hat 
thrown  out  in  front  of  it.  Fig.  5. — Case  529.  A  locoed  angora 
goat  unable  to  get  upon  its  feet,  but  otherwise  fairly  well.  Fig. 

6.— Another  attitude  of  case  529 50 

VI.  Fig.  1.— Case  3,  July  15,  1906.  Effects  of  loco  poisoning  shown 
in  emaciation  and  dejected  attitude  just  before  death  of  ani- 
mal. Fig.  2. — Inner  wall  of  fourth  stomach  of  case  3,  showing 

ulcers  u jxm  its  surface 58 

VII.  Fig.  1.— Case  2,  July  25,  1906.  Steer  bending  low  to  avoid  an 
imaginary  obstruction  above  it  while  passing  through  a  gate. 
Fig.  2.  -Case  34.  Another  case  similar  to  that  in  figure  1. 
Fig.  3.— Case  67,  May  1,  1906.  A  bright  heifer  calf  shortly  after 
birth.  Fig.  4.— Case  67,  July  5,  1906.  Calf  showing  effects  of 
loco  which  it  had  eaten  in  imitation  of  its  mother.  Fig.  5. — 
Case  67,  October  16,  1906.  Calf  with  typical  symptoms  of 
loco.  Fig.  6.— Case  67,  October  19,  1906.  Animal  just  before 
death 58 

11 


12  ILLUSTRATIONS. 

Page. 

PLATE  VIII.  Fig.  1. — Case  16,  Juno  6,  1906.  Horse  before  eating  loco  weed. 
Fig.  2. — Case  16,  September  15,  1906.  Animal  in  an  advanced 
stage  of  loco  poisoning.  Fig.  3. — Case  52,  May  19,  1906.  Mule 
in  fairly  good  condition  before  feeding  upon  loco  weed.  Fig.  4. — 
Case  52,  September  7,  1906.  Last  stages  of  loco  poisoning. 
Fig.  5.— Case  50,  July  19,  1906.  An  old  horse  before  being 
fed  with  the  loco  weed.  Fig.  .6.— Case  50,  September  18,  1906. 
Effect  of  loco  poisoning  in  attitude  and  emaciated  condition; 
also  shows  cute  produced  by  running  into  a  barbed-wire  fence. .  66 
IX.  Fig.  1. — A  group  of  locoed  sheep.  Fig.  2. — Sheep  27.  A  locoed 
sheep  in  the  last  stages  of  poisoning.  Fig.  3. — Sheep  36. 
Effect  of  loco  poisoning  combined  with  grub  in  the  head.  Fig. 
4. — Same  as  figure  3,  different  attitude.  Pig.  5. — Case  66, 
October  20,  1906.  A  locoed  lamb.  Fig.  6.— Case  66,  Novem- 
ber 12,  1906.  Attitude  of  the  animal  just  before  its  death 66 

X.  Fig.  1. — Case  4,  May  30,  1905.  Before  feeding  on  loco  weed. 
Fig.  2. — Case  4,  September  7,  1906.  Showing  typical  symp- 
toms of  loco  poisoning.  Fig.  3. — Case  4,  September  15,  1906. 
Animal  under  influence  of  loco  and  with  a  noticeable  accu- 
mulation of  serous  fluid  under  its  chin.  Fig.  4. — Case  4,  Au- 
gust 22,  1907.  Same  animal  in  succeeding  year,  when  it  no 
longer  showed  any  symptoms  of  loco  poisoning.  Fig.  5. — Case 
536,  July  9,  1906.  A  locoed  steer  with  curvature  of  the  fetlock 
joints.  Fig.  6. — Case  536,  July  25,  1906.  The  same  animal 

after  treatment  with  strychnin 76 

XI.  Fig.  1. — Case  547,  April  23, 1907.  A  heifer  in  an  advanced  stage  of 
loco  poisoning.  Fig.  2.— Case  547,  August  22, 1907.  Completely 
recovered  under  treatment.  Fig.  3.— Case  551,  June  14,  1907. 
Ahorse  in  the  advanced  stages  of  loco  poisoning.  Fig.  4. — Case 
551,  September  20,  1907.  After  course  of  treatment.  Fig.  5. — 
Case  71,  June  10,  1907.  A  locoed  sheep,  emaciated  and  ex- 
tremely nervous.  Fig.  6. — Case  71,  September  22,  1907.  Re- 
covered, as  the  result  of  the  course  of  treatment 88 

TEXT  FIGURES. 

FIG.    1.  Distribution  of  Aragallus  lamberti  in  the  United  States 37 

2.  Distribution  of  Astragalus  mollissimus  in  the  United  States 39 

3.  Case  513.     A  locoed  colt  stunted  in  its  growth  by  loco  poisoning 44 

4.  Curve  of  weight  of  steer  No.  10,  1906 58 

5.  Curve  of  weight  of  steer  No.  10,  1907 ' 59 

6.  Curve  of  weight  of  cow  No.  32 59 

7.  Curve  of  weight  of  cow  No.  37 60 

8.  Curve  of  weight  of  calf  No.  66 61 

9.  Curve  of  weight  of  calf  No.  67 62 

10.  Curve  of  weight  of  calf  No.  68 , 63 

11.  Curve  of  weight  of  horse  No.  16 63 

12.  Curve  of  weight  of  horse  No.  50 64 

13.  Curve  of  weight  of  horse  No.  52 65 

14.  Curve  of  weight  of  horse  No.  59 66 

15.  Curve  of  weight  of  steer  No.  4,  1906 76 

16.  Curve  of  weight  of  steer  No.  4,  1907 76 

17.  Curve  of  weight  of  steer  No.  40.. 78 

18.  Curve  of  weight  of  horse  No.  58 79 


ILLUSTRATIONS.  13 

Page. 

FIG.  19.  Case  28,  August  27,  1906.     Locoed  cow,  but  not  a  bad  case 80 

20.  Curve  of  weight  of  cow  No.  28,  1906 81 

21.  Curve  of  weight  of  cow  No.  28,  1907 82 

22.  Curve  of  weight  of  steer  No.  42,  1906." 84 

23.  Curve  of  weight  of  steer  No.  42,  1907 84 

24.  Curve  of  weight  of  cow  No.  35 85 

25.  Curve  of  weight  of  heifer  No.  548 , 85 

26.  Curve  of  weight  of  steer  No.  38 87 

27.  Curve  of  weight  of  heifer  No.  547 87 

28.  Curve  of  weight  of  steer  No.  555 88 

29.  Curve  of  weight  of  horse  No.  551 89 


THE  LOCO-WEED  DISEASE  OF  THE  PLAINS. 


PART  I.— INTRODUCTION. 

HISTORICAL  SUMMARY  AND  REVIEW  OF  LITERATURE. 

The  word  "loco"  is  of  Spanish  origin,  in  which  language  it  is  used 
both  as  a  noun  and  as  an  adjective,  meaning  crazy.  It  has  been 
popularly  applied  to  a  considerable  number  of  plants  in  the  semiarid 
region  of  the  Western  and  Southwestern  States  because  of  the  effects 
these  plants  are  supposed  to  produce  on  animals. 

The  first  published  account  of  the  loco  plants  was  by  Doctor  Vasey 
in  the  monthly  report  of  the  Commissioner  of  Agriculture  for  October, 
1873.  He  quotes  a  letter  from  O.  B.  Ormsby,  of  Bakersfield,  Cal., 
who  describes  the  effect  of  the  plant  in  the  following  terms : 

It  prevails  quite  abundantly  over  an  extent  of  150  square  miles  in  this  valley,  and,  I 
am  informed,  is  found  in  other  valleys  of  the  State,  and  also  in  Arizona.  This  year  the 
army-worm,  and  a  minute  insect  which  destroys  the  seeds,  have  killed  a  great  deal  of 
it,  but  if  not  molested  it  will  soon  flourish  to  as  great  an  extent  as  ever.  I  think  very 
few,  if  any,  animals  eat  the  loco  at  first  from  choice;  but,  as  it  resists  the  drought  until 
other  feed  is  scarce,  they  are  at  first  starved  to  it,  and  after  eating  it  a  short  time  ap- 
pear to  prefer  it  to  anything  else.  Cows  are  poisoned  by  it  as  well  as  horses,  but  it 
takes  more  of  it  to  affect  them.  It  is  also  said  to  poison  sheep.  As  I  have  seen  its 
action  on  the  horse,  the  first  symptom  of  the  poisoning,  apparently,  is  hallucination. 
When  led  or  ridden  up  to  some  little  obstruction,  such  as  a  bar  or  rail  lying  in  the  road, 
he  stops  short,  and,  if  urged,  leaps  as  though  it  were  four  feet  high.  Next  he  is  seized 
with  fits  of  mania,  in  which  he  is  quite  uncontrollable,  and  sometimes  dangerous. 
He  rears,  sometimes  even  falling  backward,  runs  or  gives  several  successive  leaps 
forward,  and  generally  falls.  His  eyes  are  rolled  upward  until  only  the  white  can  be 
seen,  which  is  strongly  injected,  and,  as  he  sees  nothing,  he  is  as  apt  to  leap  against  a 
wall  or  man  as  in  any  other  direction.  Anything  which  excites  him  appears  to  induce 
the  fits,  which,  I  think  are  more  apt  to  occur  in  crossing  water  than  elsewhere,  and 
the  animal  sometimes  falls  so  exhausted  as  to  drown  in  water  not  over  2  feet.  deep. 
He  loses  flesh  from  the  first,  and  sometimes  presents  the  appearance  of  a  walking 
skeleton.  In  the  next  and  last  stage,  he  only  goes  from  the  "l<x-o"  to  water  and  back, 
his  gait  is  feeble  and  uncertain,  his  eyes  are  sunken,  and  have  a  flat,  glassy  look,  and 
his  coat  is  rough  and  lusterless.  In  general,  the  animal  appears  to  perish  from  starva- 
tion and  constant  excitement  of  the  nervous  system,  but  sometimes  appears  to  suffer 
acute  pain,  causing  him  to  expend  his  strength  in  running  wildly  from  place  to  place, 
pawing  and  rolling,  until  he  falls,  and  dies  in  a  few  minutes. 

The  specimen  sent,  Doctor  Vnsey  said,  was  an  Astragalus.  In  the 
report  of  the  Commissioner  of  Agriculture  for  1S74  Doctor  Vasey 
quotes  this  same  letter  of  Ormsby  and  refers  to  other  reports  received 
from  California.  The  plants  sent  to  him  were  determined  as  As- 

15 


16  THE  LOCO-WEED   DISEASE   OF  THE  PLAINS. 

tragalus  liornii  Gr.  and  Astragalus  lentiginosus  Gr.  He  states,  too, 
in  tliis  report  that  Doctor  Moffatt,  of  the  United  States  Army,  had 
sent  in  specimens  of  Oxytropis  lamberti,  from  Colorado,  with  the  fol- 
lowing description  of  its  effects: 

Cattlemen  inform  me  that  a  weed  grows  among  the  grass,  particularly  in  damp 
ground,  which  is  poisonous  to  horned  cattle  and  horses  and  destroys  many  of  them. 
From  the  manner  in  which  they  describe  its  effects  upon  the  animals  it  must  be  of 
the  nature  of  a  narcotic,  and  they  assure  me  that  cattle,  after  having  eaten  it,  may 
linger  many  months  or  for  a  year  or  two,  but  invariably  die  at  last  from  the  effects  of 
it.  The  animal  does  not  lose  in  flesh  apparently,  but  totters  on  its  limbs  and  becomes 
crazy.  While  in  this  condition,  a  cow  may  lose  her  calf  and  never  find  it  again  and 
will  not  recognize  it  if  presented  to  her.  The  sight  becomes  affected,  so  that  the  ani- 
mal has  no  knowledge  of  distance,  but  will  make  an  effort  to  step  or  jump  over  a 
stream  or  an  obstacle  while  at  a  distance  off  and  will  plunge  into  it  or  walk  up  against 
it  upon  arriving  at  it.  The  plant  was  pointed  out  to  me,  and  seems  to  be  related  to 
the  lupin. 

In  1875  Mr.  Kellogg,  in  an  article  on  California  and  Colorado  loco 
poisons,  in  the  Proceedings  of  the  Academy  of  Sciences  of  California, 
states  that  thousands  of  horses,  cattle,  and  sheep  have  been  poisoned 
by  Astragalus  menziesii  in  California.  He  gives  a  description  also 
of  Oxytropis  lamberti. 

Professor  Prescott  in  1878  gave  an  account  of  the  attempts  of  Miss 
Watson  to  extract  a  poisonous  principle  from  Oxytropis  lamberti. 
He  states  that  Mr.  Birdsall  tried  some  of  the  ground  root  on  himself, 
but  with  little  effect. 

In  an  article  in  the  American  Journal  of  Pharmacy  in  1879  Maisch 
adds  Astragalus  moUissimus  to  the  list  of  loco  plants,  and  says  that 
he  is  informed  that  horses  dig  in  the  earth  for  it,  become  intoxicated, 
seek  water,  drink  with  avidity,  swell  up,  fall  over,  and  die. 

In  the  report  of  the  Commissioner  of  Agriculture  for  1878  Profes- 
sor Collier  refers  to  specimens  of  Oxytropis  lamberti,  which  he  says 
were  received  for  examination.  He  makes  a  brief  reference  to  the 
work  of  Miss  Watson. 

In  1880  Professor  Collier,  in  the  report  of  the  chemist  to  the 
Commissioner  of  Agriculture  for  1879,  makes  a  preliminary  report 
on  Astragalus  moUissimus  and  Oxytropis  lamberti.'  He  states  that 
as  a  result  of  the  analyses  the  only  substances  likely  to  be  poisonous 
hi  Astragalus  moUissimus  are  an  alkaloid  and  a  bitter  extractive; 
the  harm  being  done  by  Oxytropis  lamberti  probably,  by  the  fact 
that  the  sweet  taste  of  the  plant  leads  the  animals  to  eat  a  substance 
which  is  mechanically  unfit  for  food,  but  it  is  possible  that  if  the 
animal  becomes  enfeebled  the  small  amount  of  alkaloids  present 
may  produce  poisonous  effects. 

Ott,  in  1882,  in  an  article  in  "New  Remedies"  states  that  the 
loco  plants  are  Oxytropis  lamberti,  Astragalus  moUissimus,  and 
Sophora  sericea.  These. may  prove  fatal  in  two  or  three  days;  other 


REVIEW   OF  LITERATURE.  17 

cases  linger  a  year  or  more.  Horses  are  more  affected  than  cattle 
or  sheep.  When  first  eaten  an  exhilarating  effect  is  produced  which 
tempts  the  animal  to  eat  more.  Later  the  animal  contracts  the 
habit.  It  does  not  acquire  the  habit  in  summer  when  there  is  an 
abundance  of  grass.  He  then  states  that  the  effects  are  as  follows: 

1.  A  small  amount  of  exercise  will  produce  profuse  sweating. 

2.  The  animal  when  "shying",  at  an  object  is  very  liable  to  rear  up  and  fall  back- 
ward. 

3.  A  stroke,  or  even  a  touch,  about  the  head  seems  to  rouse  the  disorder,  which  is 
immediately  manifested  by  struggles  and  general  frenzy. 

4.  While  being  ridden,  when  that  is  possible,  the  animal  steps  very  high,  as  though 
walking  over  obstacles,  and  the  slightest  thing  in  the  road,  as  a  stick,  piece  of  rope, 
or  wagon  rut,  will  be  magnified  into  an  apparently  insurmountable  difficulty,  and  it 
is  ludicrous  to  see  the  animal  jump  as  though  leaping  over  a  ditch  in  an  effort  to  get 
over  it. 

5.  The  animal  loses  all  power  of  reasoning  or  of  coordination,  will  walk  into  a  ditch 
or  bank  instead  of  around  it,  and  will  sometimes  walk  backward  when  apparently 
trying  to  go  forward. 

Ott  made  an  alcoholic  extract  of  Astragalus  mottissimus  and 
treated  subcutaneously  frogs,  rabbits,  and  a  cat.  The  rabbits 
were  used  for  circulation  tests.  He  summarizes  the  results  of  his 
pharmacological  tests  as  follows: 

1.  It  decreases  the  irritability  of  the  motor  nerves. 

2.  It  greatly  affects  the  sensory  ganglia  of  the  central  nervous  system,  preventing 
them  from  readily  receiving  impressions. 

3.  It  has  a  spinal  tetanic  action. 

4.  It  kills  mainly  by  arrest  of  the  heart. 

5.  It  increases  the  salivary  secretion. 

6.  It  has  a  stupefying  action  on  the  brain. 

7.  It  reduces  the  cardiac  force  and  frequency. 

8.  It  temporarily  increases  arterial  tension,  but  finally  decreases  it. 

9.  It  greatly  dilates  the  pupil. 

In  1885  Mohr  gives  the  distribution  of  the  species,  stating  that 
they  are  found  in  New  Mexico,  Colorado,  Utah,  Nevada,  Arizona, 
and  California.  He  gives  the  following  list  of  species  as  loco  plants: 
Astragalus  mortoni,  A.  Jiornii,  A.  lentiginosus  var.  fremontii,  A. 
cocarjxi  (oocarpa  probably  intended),  A.  crotalariir,  and  Oxi/tropis 
lamberti. 

Up  to  this  time  all  reports  agree  as  to  the  poisonous  character 
of  the  plants,  but  an  anonymous  author  in  the  American  Veterinary 
.Review  of  1885  states  positively  that  the  plant  is  not  poisonous. 
He  says  that  when  cattle  eat  a  quantity  it  absorbs  the  juices  of  the 
alimentary  canal  and  dries  them  up.  It  then  collects  in  the  stomach 
and  intestines  as  a  dry  mass,  and  the  pressure  on  the  circulation 
causes  all  the  symptoms  observable  and  finally  produces  death. 
He  declares  that  the  internal  condition  of  cattle  with  this  disease 
verifies  this  view. 

79164— Bull.  112—09 2 


18  THE   LOCO- WEED  DISEASE   OF   THE   PLAINS. 

Havard  in  1885  says  that  Astragalus  mollissimus  is  the  loco  plant 
of  western  Texas.  Animals  avoid  it,  and  eat  it  only  through  inad- 
vertence or  necessity.  They  lose  appetite,  become  stupid  and  thin, 
have  tremors,  and  lose  coordination.  Oxytropis  lamberti  is  found 
only  in  northern  Texas,  and  is  nowhere  common. 

Hurd  in  1885  states  that  the  loco  plants  in  California  are  Astragalus 
crotalarise,  A.  lentiginosus ,  and  Oxytropis  lamberti.  He  says,  too, 
that  animals  eat  loco  only  when  driven  by  hunger,  but  they  soon 
crave  it  and3  wander  miles  in  search  of  it.  They  become  intoxicated, 
can  not  be  led  through  a  gate,  walk  mincmgly,  shy,  have  an  unsteady 
gait,  and  become  ataxic;  when  driven  into  water  they  may  lie  down 
and  refuse  to  rise.  They  become  emaciated  and  finally  die  of  exhaus- 
tion. Complete  recovery  never  occurs. 

In  the  Cornhill  Magazine  of  1886  there  is  an  article  entitled,  "The 
cowboy  at  home,"  in  which  is  a  somewhat  detailed  description  of 
the  phenomena  01  loco  poisoning  in  horses,  as  follows: 

We  passed  a  heap  of  about  40  dead  horses  piled  up  together,  the  most  revolting, 
pitiful  spectacle  imaginable,  and  standing  listlessly,  or  moving  about  with  staggering 
gait,  were  about  twice  as  many  more  still  living  creatures  with  a  peculiar  look  and 
manner  about  them  such  as  I  had  never  seen  before,  and  most  of  whom  must  surely 
soon  be  dragged  to  the  big  heap  close  by.  But  what  on  earth  did  it  all  mean?  It 
seemed  so  strange  suddenly  to  come  across  this  grewsome  sight  on  the  lone  prairie.  I 
soon  learned  the  explanation. 

A  weed  called  "loco"  has  of  late  years  largely  increased  in  some  of  the  cattle  ranges 
of  Texas  and  the  Indian  Territory,  owing,  probably,  to  an  increase  in  the  rainfall.  It 
has  a  mysterious  habit  of  appearing  suddenly  in  places  where  it  was  before  unknown, 
and,  given  a  dry  season,  of  as  suddenly  disappearing.  During  the  summer,  when  the 
prairie  is  a  fair  expanse  of  waving  grass,  lit  up  with  bright  flowers,  both  horses  and 
cattle  instinctively  avoid  it,  but  when  in  the  fall  of  the  year  the  grass  becomes  scarce 
in  overstocked  regions,  and  when  all  around  assumes  a  brown  and  burntrup  appear- 
ance, it  stands  out  conspicuously  and  temptingly  green,  its  long,  soft,  velvety  leaves 
rising  in  a  bunch  from  6  inches  to  a  foot  off  the  ground.  Then  the  hungry  creatures 
begin  by  nibbling,  suspiciously  and  stealthily,  at  the  seductive  plant,  but  very  soon 
become  reckless,  and  eagerly  and  greedily  devour  all  that  comes  in  their  way.  And 
now,  if  the  mania  can  not  be  nipped  in  the  bud  by  a  sufficiency  of  good  strong  food, 
the  animal  is  doomed,  for  he  has  become  a  confirmed  "loco-eater."  He  will  rapidly 
become  thin  and  lose  all  control  over  his  movements;  he  will  be  subject  to  frequent 
fits,  during  which  he  lies  on  the  ground  groaning  and  foaming  at  the  mouth;  he  throws 
himself  about  without  reason;  rears  up  or  runs  about  in  small  circles  when  you  attempt 
to  mount  him;  his  eyes  turn  dull  and  stupid;  in  short,  he  gives  you  the  impression  of 
being  bereft  of  his  senses.  Specimens  of  loco  have  been  subjected  to  analysis  by  ex- 
perts in  Washington  and  in  Edinburgh,  but  without  anything  injurious  being  dis- 
covered in  it.  It  is  possible  that  some  minute  animalculse  may  be  the  cause  of  the 
mischief,  but  up  to  the  present  its  disastrous  effects  only  are  known,  for  this  pernicious 
weed  causes  periodically  the  death  of  thousands  of  horses  and  cattle. 

Professor  Sayre,  of  the  University  of  Kansas,  in  1886  published 
in  the  Transactions  of  the  Kansas  Academy  of  Sciences  a  somewhat 
extended  account  of  loco  and  locoed  animals.  He  visited  New 
Mexico,  Colorado,  and  Kansas,  and  states  that  the  plant  appears  at 


REVIEW   OF   LITEKATUBE.  19 

Medicine  Lodge  and  extends  southwesterly  into  the  Indian  Territory 
and  northwesterly  through  Kansas.  He  says  that  a  veterinary  sur- 
geon, Doctor  Harding,  took  two  horses  with  a  taste  for  loco,  and  kept 
one  in  a  pasture  with  loco  and  the  other  in  a  loco-free  pasture,  with 
the  result  that  the  one  died  and  the  other  recovered.  Two  others 
were  fed,  one  with  hay  and  the  other  with  dead  loco.  The  first  one 
lived  and  the  second  died.  He  gives  a  description  of  the  symptoms 
of  locoed  animals,  the  result  of  his  personal  inquiry  among  ranchmen 
and  the  report  of  a  Mr.  R.  E.  Steele.  It  is  somewhat  interesting, 
however,  that  many  parts  of  this  description  agree  word  by  word, 
and  sentence  by  sentence,  with  a  letter  of  Mr.  Ormsby  quoted  in 
Vasey's  report  of  1873. 

Sayre  states  that  the  loco  disease  is  due  to  two  plants,  Astragalus 
niollissimus  and  Oxytropis  lamberti.  He  made  a  preliminary  chemical 
examination  which  was  apparently  never  completed.  lie  also  held 
an  autopsy  on  a  locoed  cow  belonging  to  Mr.  Steele.  The  cow  was 
undersized,  poor,  stupid,  unsteady,  with  short  breathing  and  shaking 
head.  lie  reports  that  the  reticulum  and  psalterium  were  softened. 
The  tissues  through  the  intestines  were  degenerated ;  the  peritoneum 
and  the  omentum  were  inflamed  with  tumors  the  size  of  a  pea;  the 
heart  was  one-third  larger  than  normal,  with  the  mitral  and  tricuspid 
valves  inflamed;  the  bile  was  thin  and  watery,  and  the  inner  coat 
of  the  bladder  softened;  the  membranes  of  the  brain  were  congested 
and  adherent,  the  brain  was  paler  than  normal,  and  the  membranes 
of  the  spinal  cord  were  inflamed  and  adherent.  He  concludes  that 
the  disease  is  one  of  the  mucous  and  serous  membranes. 

In  the  same  year  Professor  Sayre  published  an  article  in  the  report 
of  the  Kansas  State  board  of  agriculture,  which  was,  to  a  large  extent, 
a  repetition  of  the  material  published  in  the  Transactions  of  the 
Kansas  Academy  of  Sciences.  lie  adds,  however,  a  report  that  the 
plant  causes  abortion  in  cows.  He  states  that  as  the  result  of  his 
own  chemical  examination  it  would  appear  that  there  is  no  poisonous 
principle  in  the  plant,  and  suggests  that  the  hairs  upon  the  leaves  may 
be  irritating. 

In  the  Third  Annual  Report  of  the  Bureau  of  Animal  Indnstrv  /or 
1SSO  Doctor  Stalker  gives  a  report  of  a  personal  investigation  of  the 
loco  disease.  He  visited  the  country  from  western  Nebraska  to 
Salt  Lake,  and  from  Cheyenne  to  El  Paso.  He  describes  the  appear- 
ance and  habits  of  the  two  plants,  ()jri/tro]>in  Idinbcrti  and  Afttmyalufi 
nioUitstsiinuti.  He  states  that  the  term  loco  is  used  simplv  to  desig- 
nate a  certain  disease,  as  well  as  being  a  term  applied  to  plants. 

lie  found  that  the  loco  habit  is  an  acquired  one  and  that  animals 
will  forget  it  when  kept  on  loco-freo  food.  All  confirmed  loco-raters 
become  complete  physical  wrecks,  showing  general  derangement 
of  the  nervous  system  and  more  or  less  digestive  disturbance.  In 


20  THE   LOCO- WEED  DISEASE   OF   THE   PLAINS. 

post-mortem  examinations  of  horses  he  found  a  serous  effusion  in 
the  lateral  ventricles,  hemorrhagic  clots  in  the  fourth  ventricle,  and 
sometimes  a  serous  effusion  in  the  arachnoid  space.  The  liver  was 
dense  in  structure.  Immense  numbers  of  bots  were  found,  especially 
in  the  duodenum,  and  he  suggests  that  while  these  parasites  would 
not  account  for  the  clinical  symptoms,  they  may  have  something  to 
do  with  the  abnormal  appetite.  In  post-mortems  on  sheep  large 
numbers  of  tapeworms  were  found,  and  these  he  suggests  may  account 
in  part  for  the  loco  appetite  in  sheep.  He  presumes  that  the  plant 
is  possessed  of  some  toxic  property  that  has  a  specific  effect  on  the 
nerve  centers,  and  that  these  effects  have  a  marked  tendency  to 
remain  permanent,  though  he  was  not  aware  that  the  poison,  if 
present,  had  ever  been  separated  by  analysis.  He  states  that  the 
disease  may  be  cured  by  taking  animals  from  the  range  and  feeding 
them  on  nutritious  diet.  He  also  states  that  special  attention 
should  be  given  to  the  destruction  of  intestinal  parasites,  and  ex- 
presses his  belief  that  thousands  of  supposed  cases  of  loco  poisoning 
are  the  result  alone  of  such  parasites. 

In  1887  Behr,  in  an  article  on  the  poisonous  plants  indigenous  to 
California,  states  that  the  notorious  loco  weed  is  an  Astragalus,  but 
that  the  exact  species  is  not  known  with  certainty.  He  says  that 
dogs,  cats,  and  rabbits  do  not  suffer  if  the  seeds  or  herbs  are  mixed 
with  their  food,  and  that  cattle,  sheep,  and  horses  suffer  only  at  cer- 
tain seasons.  Poisoning  may  be  due  either  to  infection  by  some 
fungoid  parasite,  perhaps  of  the  Claviceps  order,  or  by  a  substance 
produced  by  fermentation  or  putrefaction,  or  it  is  possible  that  the 
poison  may  not  be  of  vegetable  origin  at  all,  but  caused  by  some 
parasite  infesting  the  suspected  plant. 

Carhart,  in  the  New  York  Medical  Record  in  1887,  speaks  of  his 
acquaintance  with  the  effects  of  loco  in  the  Panhandle.  Cattle 
occasionally  eat  it,  but  are  rarely  affected  by  it;  mules  do  not  suffer 
from  it;  but  cow  ponies  die  by  the  thousand.  If  the  taste  is  acquired 
they  will  leave  green  grass  to  hunt  for  it.  They  break  down  rapidly, 
become  weak,  staggering,  foolish,  and  crazy. ^  A  tap  on  the  head 
will  cause  them  to  stagger,  rear,  and  fall  backward.  Vision  is  im- 
paired, and  there  is  a  loss  of  muscular  coordination.  The  Indians  say 
that  it  is  due  to  an  insect,  but  the  author  has  found  none.  Carhart 
drank  a  decoction  of  loco  without  effect,  and  administered  the  decoc- 
tion to  a  locoed  horse  with  apparent  good  results. 

In  the  Homeopathic  Recorder  in  1887  Doctor  Gee  gives  a  somewhat 
detailed  account  of  some  experiments  made  by  some  of  his  students 
who  took  doses  of  loco  extract.  There  seems  to  be  no  uniformity 
in  the  reports  that  these  students  made.  They  tell  of  an  infinite 
number  of  symptoms,  many  of  which,  apparently,  must  have  been 
imaginary. 


REVIEW  OF  LITEEATUEE.  21 

Dr.  T.  E.  Wilcox,  of  the  United  States  Army,  writes  to  the  Medical 
Record  in  1887  on  the  subject  of  loco,  and  states  that  the  treatment 
employed  by  the  cowboys  in  Idaho  consists  in  the  amputation  of  the 
tails  of  the  animals  affected.  They  claim  that  they  seldom  lose  any 
stock  when  this  treatment  is  instituted  early  enough.  The  writer 
adds  that  paralysis  is  probably  due  to  congestion  of  the  spinal  coi'd. 
It  affects  the  posterior  members  first.  The  pupils  are  dark,  as  after 
the  use  of  eserin.  Oxytropis  lamberti,  Astragalus  mollissimus,  and  pos- 
sibly others  of  the  Leguminosae  are  charged  with  producing  loco  poi- 
soning. In  Idaho  the  cowboys  call  these  plants,  larkspur,  although 
true  larkspur  is  rarely  found  in  the  line  of  march  and  at  that  season  of 
the  year. 

Kingsley  in  1888  refers  to  Kennedy's-work,  which  was  at  that  time 
unpublished,  and  gives  cases  of  locoed  mules,  with  report  of  a  post- 
mortem. In  a  second  letter  he  concludes  that  the  mules  suffered 
from  colic,  and  this,  from  his  report  of  the  symptoms  and  the  post- 
mortem, would  seem  to  be  probable.  He  concludes  that  the  loco  plant 
is  not  poisonous  and  that  the  symptoms  and  pathology  are  such  as 
would  result  from  overfeeding  with  any  green  feed. 

Kennedy  in  1888,  after  a  description  of  the  plant,  tells  of  his  at- 
tempts at  analysis.  He  discovered  no  alkaloid  and  separated  no 
poisonous  principle.  He  experimented  with  infusions  in  boiling 
water,  with  dried  powder,  and  with  an  organic  acid  separated  from 
the  plant.  He  fed  these  materials  to  a  dog  and  there  was  no  effect. 
He  concludes  that  the  plant  is  not  poisonous  and  that  ill  effects,  if  any, 
are  produced  by  the  tough,  fibrous,  indigestible  character  of  the  plant 
acting  as  a  foreign  body,  or  else  its  action  is  identical  with  an  overload 
of  any  kind. 

The  St.  Louis  Medical  and  Surgical  Journal  in  an  editorial  article  a 
little  later  refers  to  Kennedy's  work,  and  criticizes  him  for  trying 
physiological  experiments  on  a  dog  rather  than  on  an  herbivorous 
animal,  and  considers  his  results  of  no  value. 

Klencli  in  1888  gives  a  general  description  of  symptoms,  referring 
to  the  papers  of  Say  re  and  Stalker,  and  advises  as  remedies  the  admin- 
istration of  potassium  bromid  or  belladonna  and  aloes,  and  bleeding. 

In  18S8  Miller  writes  of  the  geographical  distribution  of  Oxytropis 
lamberti  and  Astragalus  mollissimus  and  gives  a  description  of  the 
plants.  His  description  of  the  effect  of  the  weeds,  as  well  as  his 
remarks  in  regard  to  the  distribution,  are  apparently  derived  from 
Sayre's  publications.  He  makes  the  suggestion  that  inasmuch  ns 
loco  is  said  to  produce  abortion  it  may  be  that  the  plant  might  be  used 
as  an  emmenagogue. 

Say  re  in  1888,  in  a  paper  published  in  the  Kansas  State  board  of 
agriculture  report,  adds  to  what  he  has  written  in  preceding  papers  a 
summary  of  the  results  of  Kennedy  and  of  Ott,  and  states  that  he 


22  THE   LOCO- WEED   DISEASE   OF   THE   PLAINS. 

has  tried  the  extract  on  himself,  but  with  no  result.  In  the  same  year, 
in  the  Proceedings  of  the  Kansas  Pharmaceutical  Association,  he 
"reports  what  he  has  written  before  and  seriously  questions  the  exist- 
ence of  poisonous  properties  in  the  plants,  considering  that  the 
effects  may  be  due  to  malnutrition,  brought  about  in  part  by  feeding 
on  this  weed. 

Schwarzkopff  in  1888  published  his  experience  with  locoed  ani- 
mals in  Texas,  detailing  the  symptoms  in  very  much  the  same  terms 
as  those  used  by  previous  authors.  He  used  as  a  remedy  atropin 
and  morphia  sulphate  applied  hypodermically.  The  horse  was  quiet 
and  acted  sensibly  in  six  days.  He  reports  a  post-mortem  on  another 
horse.  He  found  the  cranial  sinuses  filled  with  a  straw-colored  fluid, 
the  vessels  of  the  pia  mater  injected,  and  the  gray  substance  reddened 
and  edematous.  On  the  base  of  the  brain  inside  the  arachnoid 
membrane  he  found  a  teaspoonful  of  pinkish  fluid.  The  medulla 
and  cord  were  edematous  and  moist  on  cut  surface. 

In  1889  McEachran  reports  an  autopsy  near  Livermore,  Colo.  He 
watched  100  cases  of  locoed  sheep  at  Givens  Ranch,  near  Colorado 
Springs,  and  made  post-mortem  examinations  of  two,  no  details  of 
which  are  published  with  the  report. 

In  1889  Anderson  describes  the  symptoms  of  locoed  animals.  He 
says  that  the  animal  has  unnaturally  bright  eyes,  froths  at  the 
mouth,  exhibits  extreme  salivation,  or  sometimes  the  mouth  may  be 
hot  and  dry.  The  appetite  is  lost  and  an  offensive  gas  is  belched 
forth.  The  animal  loses  control  of  the  limbs,  and  sometimes  the 
muscles  of  the  neck  are  contracted  on  one  side.  It  becomes  stupid, 
falls,  and  rarely  rises  again.  It  may  die  in  a  few  hours  or  lie  for  a 
week.  He  reports  a  post-mortem  in  which  the  intestines  and  sur- 
rounding fat  were  green  immediately  after  death.  The  arteries  and 
smaller  vessels  in  the  limbs  were  gorged  with  thick  dark  blood. 
The  lining  of  the  first  stomach  was  worn  and  ulcerated  in  patches 
and  in  some  cases  decomposition  seemed  to  have  commenced ;  it  was 
very  soft  and  could  be  peeled  off  the  muscular  layer  in  big  pieces.  The 
lungs  and  heart  were  almost  bloodless,  and  the  brain  was  purplish, 
soft,  and  pulpy.  He  states,  however,  that  the  symptoms  vary  in 
different  cases.  He  lists  as  loco  plants  Oxytropis  lamberti,  Leucocri- 
num  montanum,  Fritilla.iia  pudica,  and  ZygaJenus  elegants. 

In  1889  Dr.  Mary  G.  Day,  in  two  articles  in  the  New  York  Medical 
Journal,  describes  the  process  which  she  followed  in  attempting  to 
separate  a  poison  from  loco  plants  and  gives  the  result  of  some  phar- 
macological experiments  with  a  decoction.  She  fed  the  decoction  to  a 
cat  and  found  disturbing  sj^mptoms  in  two  days.  There  was  less 
activity,  the  coat  became  rough,  the  appetite  was  lost,  fondness  for 
loco  was  induced,  and  there  was  diarrhea,  retching,  and  vomiting. 
Emaciation  increased  until  the  eighteenth  day,  when  convulsions 


REVIEW   OF   LITERATURE.  23 

occurred.  There  were  alternate  periods  of  excitement  and  quiet  for 
36  hours,  when  the  posterior  extremities  became  paralyzed,  and  the 
animal  died  in  about  two  hours.  The  post-mortem  examination 
showed  ulcers  in  the  stomach  and  duodenum.  The  heart  was  in 
diastole  and  anemic.  In  the  second  case  she  found  similar  symptoms 
but  no  periods  of  excitement.  This  cat  died  on  the  thirteenth  day. 
Two  cats  were  confined  and  treated  in  the  same  way,  except  that  one 
was  fed  loco.  The  loco-fed  animal  acquired  the  disease,  while  the 
other  remained  well.  In  Michigan  experiments  on  frogs  and  kittens 
caused  nervous  twitchings  and  death.  A  jack  rabbit  was  fed  on  milk 
and  grass,  then  fresh  loco  was  substituted  for  the  grass.  It  acquired 
the  habit  and  died  in  ten  days,  with  the  head  thrown  back  and  with 
the  stomach  ruptured.  Doctor  Day  states  that  more  poison  is  pres- 
ent in  the  plants  in  the  fall  and  winter.  She  reached  the  following 
conclusions : 

1.  There  is  some  poison  in  loco  weed  which  may  cause  the  illness,  and,  if  sufficient 
quantity  is  taken,  the  death  of  an  animal. 

2.  This  poison  is  contained  in  the  decoction  obtained  from  the  plants,  and  by  sys- 
tematically feeding  it  to  healthy  cats  cases  of  loco  disease  may  be  produced. 

3.  A  taste  for  the  green  loco  weed  may  be  experimentally  produced  in  the  jack 
rabbit. 

4.  From  the  large  quantity  of  the  plant  or  of  the  decoction  required  to  produce  the 
disease,  the  poison  must  be  weak,  or,  if  strong,  it  must  be  in  very  small  amount. 

In  the  Druggists'  Bulletin  of  1889  is  a  resume  of  the  work  on  loco  up 
to  that  date.  Miss  Day's  work  is  criticized  as  valueless  because  of  the 
lack  of  control  experiments.  The  article  is  generally  skeptical  in 
regard  to  the  existence  of  a  specific  poison  in  the  loco  plant. 

In  1889  Power  reported  upon  a  chemical  examination  of  loco, 
and  later,  in  1891,  Power  and  Cambier  made  another  report.  The 
general  result  of  their  work  was  negative.  They  showed  both  in 
Astragalus  and  Crotalaria  a  very  small  amount  of  toxic  alkaloids. 

In  1889,  in  the  Druggists'  Bulletin,  Professor  Sayre  reviews  his 
preceding  work  in  regard  to  the  loco  plants,  gives  drawings  of  two 
species,  Oxytropis  lamberii  and  Astragalus  moUissimus,  and  reports 
the  detail  of  a  chemical  examination  of  these  plants.  lie  also  states 
that  he  has  performed  certain  physiological  experiments,  but  does 
not  report  them  in  this  paper.  lie  gives  quite  fully  the  result  of 
the  work  of  Doctor  Ott,  and  then  states  that  his  own  physiological 
experiments  have  all  given  negative  results.  He  does  not  claim 
that  the  weed  is  not  poisonous,  but  apparently  does  make  the  claim 
that  nothing  is  proven  as  yet  in  regard  to  its  poisonous  properties. 

Curtice,  in  1889,  in  his  report  upon  the  animal  parasites  of  sheep, 
quotes  the  report  of  the  autopsy  by  Faville  on  locoed  sheep,  in  which 
he  found  numbers  of  ttcnite.  The  author  says  that  the  description 
of  locoed  sheep  applies  equally  well  to  those  infested  with  tjrniic; 
that  it  is  difficult  to  separate  the  symptoms  of  the  two  diseases,  and 


24  THE   LOCO-WEED  DISEASE   OF   THE   PLAINS. 

many  cases  of  locoed  animals  are  victims  of  tapeworms.  That  the 
taeniae  may  tend  to  produce  depraved  appetites  or  the  morbid  craze 
for  particular  food  is  also  a  reason  for  suspecting  that  the  loco  disease 
may  depend  in  part  on  the  tapeworm  disease. 

Sayre,  in  1890,  in  the  report  of  the  Kansas  board  of  agriculture, 
gives  the  result  of  Miss  Day's  paper,  in  which  she  tells  of  the  separa- 
tion of  crystals  which  she  considered  the  poisonous  principle.  Sayre 
produced  the  same  crystals  and  considers  them  inorganic.  He  says 
he  himself  has  separated  a  crystalline  organic  substance  but  has  not 
carried  the  investigation  further. 

An  article  by  Pammel,  in  1891,  states  that  Astragalus  moUissimus 
and  Oxytropis  lamberti  are  called  loco  plants  by  ranchmen.  Crota- 
laria  is  the  cause  of  loco  in  Iowa.  In  Australia  a  species  of  Gompho- 
lobium  is  a  loco.  He  adds,  also,  as  loco  plants  Malvastrum  coccineum 
and  Physostigma  venenosum.  He  does  not  distinguish  any  difference 
in  the  specific  effects  of  Astragalus  and  Aragallus.  He  also  calls 
Stipa  viridula  a  loco  weed. 

In  1892  McCullaugh  gives  a  description  of  the  pathological  effects 
in  locoed  horses.  He  says  that  all  herbivorous  animals,  even  ante- 
lopes, are  liable  to  the  disease.  The  disease  was  first  noticed  west 
of  the  Rio  Grande  years  ago.  Since  then  the  weed  has  been 
carried  by  birds  and  the  continuity  of  the  wind  to  the  upper  Mis- 
souri, into  old  Mexico,  the  Gulf  of  California,  and  California.  The 
action  of  the  plant  is  similar  to  that  of  alcohol  or  opium.  The  weed 
becomes  green  while  the  snow  is  on  the  ground.  Among  the  first 
symptoms  are  loss  of  flesh,  general  lassitude,  and  impaired  vision. 
The  last  may  be  taken  as  the  first  symptom.  After  the  animal  begins 
to  become  viciously  shy  an  exostosis  appears  in  the  middle  and  supe- 
rior portion  of  the  frontal  bone,  becoming  at  times  as  large  as  a 
pullet's  egg,  and  remains  permanently.  The  animal  exists  in  this 
condition  from  ten  to  eighteen  months,  but  sometimes  it  will  live  not 
over  three  months.  As  the  disease  advances  the  animal  loses  mus- 
cular power  and  tetanic  symptoms  appear.  It  will  invariably  fall  if 
suddenly  startled.  The  muscles  of  the  mouth  and  tongue  become 
partially  paralyzed,  so  that  it  is  impossible  to  take  food.  The  author 
has  many  times  offered  water  to  locoed  horses  that  he  knew  had  not 
drunk  in  five  or  six  days.  They  would  sometimes  gaze  stupidly  for 
hours  at  a  time  at  a  trough  of  water,  but  make  no  attempt  to  drink. 
The  true  cause  of  death  is  starvation. 

In  1892  Sayre,  in  the  Thirteenth  Report  of  the  Kansas  board  of 
agriculture,  after  a  resume  of  his  previous  papers,  states  that  he  has 
been  able  to  separate  an  alkaloid,  but  that  it  was  not  poisonous,  and 
his  conclusions  are  that  there  is  a  disease  having  a  mysterious  con- 
nection with  Astragalus  and  allied  genera.  He  quotes  a  letter  from 
Professor  Harshbarger,  of  Topeka,  which  states  that  animals  hunt 


REVIEW   OF   LITERATURE.  25 

loco,  become  nervous  and  later  crazy ;  that  they  bite  at  water  instead  of 
drinking  it,  their  eyesight  becomes  affected,  and  they  become  vicious 
and  emaciated.  Sayre  then  gives  Harshbarger's  opinion  in  regard  to 
loco,  which  is  skeptical  and  negative.  He  suggests  that  the  disease 
may  be  caused  by  other  things,  as  hot  weather  or  stagnant  water. 

He  also  quotes  a  letter  from  Mr.  Mayrath,  of  Dodge  City,  who 
states  that  he  had  18  cattle  eating  loco  in  November,  and  that  all 
died  before  May  1,  although  well  fed.  He  says  that  cattle  and  horses 
eat  loco  for  the  most  part  in  the  late^fall  and  winter;  that  they  eat 
it  grubs,  eggs,  and  all.  He  suggests  a  connection  of  the  grubby  stem 
with  the  disease,  and  says  he  has  been  told  of  a  man  who  was  killed 
inside  of  twenty-four  hours  by  loco  tea. 

Sayre  then  gives  a  resume  of  Doctor  Mayo's  paper,  and  in  conclu- 
sion gives  an  instance  of  a  horse  having  loco  disease,  although  it  had 
never  seen  the  loco  plant. 

Schuchardt,  in  1892,  in  the  Deutsche  Zeitschrift  fur  Thiermedicin, 
has  an  article  on  the  loco  disease  of  horses  and  cattle,  in  which  he 
gives  a  careful  and  accurate  resume  of  the  literature  up  to  date,  but 
adds  nothing  to  what  has  been  said  in  earlier  publications. 

In  the  same  year  Dr.  B.  F.  Stalker,  in  the  Medical  Current,  Chicago, 
states  that  as  early  as  1849  the  Indians  along  the  Missouri  River  told 
of  a  plant  found  in  Kansas,  Texas,  and  along  the  foothills  as  far 
north  as  Wyoming  which  would  produce  death,  preceded  by  erratic 
forms  of  excitement.  They  said  it  affected  cattle  and  horses,  and 
the  Mexicans  claimed  a  similar  effect  on  man.  The  author  describes 
Astragalus  mollissimus  and  Oxytropis  lamberti,  and  states  that  abortion 
is  sometimes  produced  by  eating  loco. 

O'Brine,  in  1893,  in  a  bulletin  of  the  Colorado  State  Agricultural 
College,  gives  a  review  of  preceding  literature,  quoting  especially  from 
Faville.  In  1889  Astragalus  mollissimus  and  Oxi/trojns  lamberti  were 
fed  to  a  sheep  at  the  college,  with  no  results.  He  states  that  the  Colo- 
rado law  offering  a  bounty  for  the  destruction  of  loco  plants  was 
passed  March  14,  1881,  and  repealed  in  April,  1885.  It  cost  the  State 
$50,000  a  year. 

O'Brine  tried  to  separate  the  poisonous  principle,  and  failed.  He 
found  the  same  reactions  for  alfalfa  that  he  obtained  for  loco.  lie 
made  tests  with  rabbits,  with  no  results.  He  made  a  number  of 
autopsies  near  Livermore,  and  'found  a  clot  at  the  base  of  the  brain 
in  all  cases.  lie  suggests  that  the  effects  of  the  loco  are  not  direct, 
but  dependent  upon  some  digestive  processes. 

Williams,  in  1893,  in  the  bulletin  of  the  South  Dakota  Agricultural 
College,  gives  a  list  of  the  plants  supposed  to  cause  loco  in  South 
Dakota.  They  include  Astragalus  mottissimus,  A.  lotiflorus,  A.  l>i- 
sulcatus,  A.  haydeniensis,  and  Oxytropis  lamberti.  He  describes  the 
plants  and  general  effects  on  the  stock,  quoting  Vasey  and  Mayo. 


26  THE   LOCO-WEED  DISEASE   OF   THE  PLAINS. 

In  1 893  Professor  Mayo  published  a  general  article  on  the  subject  of 
loco,  in  which  he  not  only  described  the  symptoms  in  much  the  same 
terms  as  former  authors,  but  gave  the  results  of  some  personal 
examinations  of  his  own.  He  says  that  the  old  inhabitants  of  south- 
western Kansas  say  it  is  more  abundant  upon  ranches  where  Mexican 
sheep  were  pastured  in  an  early  day.  He  found  on  the  roots  two 
species  of  Tineidae,  and  upon  the  plant  a  Bruchus  and  a  Curculionid. 
He  tried  extracts  of  the  dried  plant  and  the  fresh  leaves  on  guinea 
pigs,  but  with  no  results.  Both  guinea  pigs  and  cattle  refused  to  eat 
the  plant.  He  ate  it  himself  with  no  ill  effects,  and  concluded  that 
the  weed  was  not  the  cause  of  the  disease,  but  when  he  made  observa- 
tions in  the  field  he  changed  his  mind.  He  found  that  animals 
acquire  a  taste,  wander  off  alone,  lose  flesh,  and  have  a  stiff  and 
stilted  action  of  the  legs.  When  lying  down,  they  have  difficulty  in 
rising,  the  head  trembles,  the  dependent  parts  of  the  body  swell;  they 
have  a  vacant  stare,  though  they  are  not  blind,  and  they  do  not  shed 
their  hair  in  the  spring.  They  can  be  led  only  with  great  difficulty, 
shy  violently,  and  are  subject  to  crazy  fits,  especially  when  driven 
hard.  Locoed  animals  never  fully  recover. 

In  post-mortems  he  found  a  large  amount  of  serum  in  the  body 
cavity,  the  intestines  atonic,  spleen  small,  liver  small,  pale,  and  ad- 
herent to  the  diaphragm.  The  rumen  was  full  of  loco.  The  menin- 
ges  of  the  brain  were  thickened  and  congested.  The  brain  was 
smaller  than  normal,  and  firmer,  and  the  gray  tissue  was  darker  than 
normal  and  thinner  on  the  cerebrum.  In  the  central  white  substance 
of  one  brain  were  three  small  gelatinous  translucent  spots  about  the 
size  of  a  small  pea.  Sections  of  the  brain  showed  atrophy.  Pur- 
kinje's  kidney  cells  in  some  cases  had  disappeared ;  in  other  cases  the 
processes  were  atrophied.  There  were  no  changes  in  the  spinal  cord. 
His  conclusion  was  that  there  was  no  evidence  of  a  narcotic  principle 
in  the  plant,  and  that  the  animals  died  from  malnutrition  or  mal- 
assimilation  produced  by  eating  the  loco  plants.  The  cause  of  the 
delirium  may  be  clots  or  thrombi  in  the  brain,  as  these  are  apt  to  be 
formed  during  wasting  and  debilitating  diseases.  He  suggests  as 
treatment  removing  the  animals  from  loco  plants  and  giving  them 
some  good  condition  powders. 

In  the  Medical  Century  of  1893  Doctor  Givens  writes  on  the  sub- 
ject of  loco,  or  "crazy  weed,"  or  Astragalus  moUissimus.  He  de- 
scribes the  plant  in  general  and  the  effect  upon  animals  of  eating, 
much  as  had  already  been  described  by  preceding  authors.  He  then 
states  that  he  had  secured  from  Colorado  some  of  the  dried  root  of 
Astragalus  moUissimus,  from  which  he  prepared  a  tincture  and  tested 
its  effect  when  given  as  a  medicine  upon  three  cases  of  insanity,  each 
of  which  had  hallucinations  of  sight  and  hearing.  The  net  result  of 
his  investigations  was  that  loco  has  no  effect  on  insane  patients,  and 


REVIEW  OF  LITERATURE.  27 

there  is  no  reason  to  think  that  it  can  be  used  to  advantage  in  the 
treatment  of  mental  disorders.  He  concludes  that  it  is  harmless, 
even  when  taken  in  large  doses,  although  it  may  at  the  same  time 
have  a  poisonous  action  on  herbivorous  animals,  as  claimed  by 
others. 

In  the  report  of  the  Canadian  Experimental  Farms  in  1893  Fletcher 
mentions  the  fact  that  the  subject  of  loco  weeds  has  been  brought 
to  their  attention  by  the  poisoning  of  sheep  and  lambs  in  Manitoba, 
and  suggests  that  owners  of  herds  should  send  in  specimens  of  the 
plants  in  order  that  the  reports  may  be  verified. 

W.  Thornton  Parker,  in  1894,  describes  the  symptoms  of  loco 
poisoning  as  seen  by  him  in  Texas  and  New  Mexico.  Describing  the 
plant,  which  seems  to  have  been  Astragalus  mollissimus,  he  suggests 
that  beneficial  results  can  be  obtained  by  treating  the  affected 
animals  with  muriate  tincture  of  iron  with  accessories  of  hygienic 
treatment. 

In  the  same  year  Professor  Mayo  describes  much  more  fully  than 
in  his  earlier  article,  and  very  accurately,  the  symptoms  of  loco 
poisoning.  He  speaks  of  the  dropsical  swellings  which  sometimes 
occur  in  the  dependent  parts  of  the  body.  Locoed  animals  walk 
with  a  peculiar  creeping  gait  that  is  recognized  by  those  familiar  witli 
the  disease.  No  pojsonous  principle  was  found,  and  he  reiterates  his 
former  conclusion  that  the  loco  disease  is  the  result  of  malnutrition. 

In  1895  Kuedi  reports  an  examination  of  supposed  locoed  sheep  in 
Estes  Park,  Colo.  He  found  their  temperatures  low — between  86° 
and  100°  F. — with  breathing  stertorous,  pulse  slow,  abdomen  dis- 
tended, and  diarrhea  present.  In  the  autopsies  he  found  them  anemic, 
the  intestines  filled  with  gases,  the  liver  enlarged  and  filled  with 
blood,  the  kidneys  congested,  and  the  bladder  distended.  The  heart 
was  in  diastole  and  the  brain  bloodless.  He  prepared  solutions  and 
fed  rabbits.  All  passed  through  a  period  of  excitement  which  the. 
author  explains  as  caused  by  the  brain  anemia,  followed  by  a  period 
of  dullness.  They  were  observed  for  a  period  of  ten  days.  None 
died,  but  they  were  killed  for  autopsy.  In  all  cases  there  was 
congestion  of  the  abdomen  and  anemia  of  the  brain.  He  separated  a 
base  which  he  called  "locoin"  and  an  acid,  and  states  that  locoin  is 
not  poisonous,  but  that  the  acid  is.  He  refers  to  the  loco  as  "white 
loco"  or  Astragalus  moUiftfrimus.  It  is  difficult  to  tell  what  species  he 
was  dealing  with,  but  it  seems  more  likely  that  it  was  Arafjattuf* 
lamkerti.  It  may  be  said  in  regard  to  his  work  that  there  seems  to  be 
no  evidence  that  the  sheep  examined  by  him  had  eaten  loco,  and  the 
symptoms  and  the  autopsies  lead  the  present  author  to  conclude  that 
they  did  not  have  the  loco  disease  at  all. 

In  1896  Nocholds,  in  the  American  Veterinary  Review,  gives  his 
experience  while  driving  a  bunch  of  horses  from  southern  to  north- 


28  THE   LOCO- WEED   DISEASE   OP   THE   PLAINS. 

western  Texas.  Some  of  them  gradually  acquired  the  loco  habit. 
One  of  them  wandered  from  the  bunch,  walked  high,  had  a  staring 
coat,  glassy  eyes,  and  could  not  be  driven.  Some  of  them  showed 
the  effect  only  when  excited  or  driven  hard.  All  were  stupid.  All 
affected  animals  were  mares  over  6  years  old,  and  23  out  of  300  died 
within  a  year.  The  author  thinks  there  is  no  cure. 

In  1897  Mr.  J.  IT.  Maiden,  in  the  Report  of  the  Department  of 
Agriculture  of  Sydney,  New  South  Wales,  in  a  discussion  of  poisonous 
plants  in  that  locality,  mentions  the  " indigo  disease"  of  Australia  as 
probably  identical  with  the  loco  disease  of  the  United  States,  and  in 
connection  with  this  he  quotes  O'Brine  in  regard  to  the  loco  disease. 

In  1898  Professor  Sayre  published  in  the  Kansas  Medical  Journal  a 
repetition  of  his  former  statements,  and  concludes  with  this  state- 
ment: T'We  feel  warranted  in  saying  that  the  so-called  poison  is  a 
development  within  the  animal,  and  not  a  product  preexisting  in  the 
weed  itself." 

In  1899  Prof.  S.  B.  Nelson,  of  the  Washington  Agricultural  College, 
in  a  report  on  experiments  on  feeding  wild  plants  to  sheep,  states  that 
he  has  fed  small  amounts  of  Astragalus  spaldingii,  Astragalus  palou- 
sensis,  and  Astragalus  dorycnioides,  but  without  any  bad  results. 

In  the  Annual  Report  of  the  Department  of  Agriculture  of  the 
Northwest  Territories  in  1899,  T.  N.  Willing  refers  to  the  abundance 
of  Oxytropis  lamberti  in  the  Territories  and  expresses  his  surprise 
that  there  is  not  more  trouble  from  it. 

In  an  article  on  the  ethno-botany  of  the  Coahuila  Indians  of 
southern  Calif ornia,  Barrows  in  1900  refers  to  the  genus  Astragalus, 
known  as  "rattlesnake  weed"  or  "loco  weed"  in  California.  He 
says  that  several  species  are  poisonous  to  cattle,  sheep,  men,  and 
horses.  One  species,  he  states,  is  used  by  the  Coahuila  Indians  as 
a  flavoring  principle,  and  according  to  another  author  dry  pods  are 
pounded  up  and  mixed  with  beans  and  perhaps  other  articles  of  food 
as  a  spice. 

In  Law's  work  on  veterinary  medicine,  published  in  1901,  is  a 
general  review  of  the  subject  of  loco,  concluding  with  a  special  report 
of  Miss  Day's  work. 

In  the  Annual  Report  of  the  Bureau  of  Animal  Industry  for  1900 
E.  V.  Wilcox  states  that  Astragalus  spicatus  is  the  most  important 
loco  plant  of  Montana.  Besides  this  species  there  are  Astragalus 
splendens  and  Astragalus  lagopus,  which  are  harmful.  He  disproves 
the  belief  that  the  loco  disease  may  be  caused  by  alkali,  and  gives 
an  account  of  the  characteristics  of  the  disease  and  the  details  of  an 
acute  case  of  a  sheep  which  died  in  four  days.  He  states  that  the 
disease  in  cattle  is  rare.  In  autopsies  on  sheep  a  slight  congestion 
of  the  brain  is  noticed,  the  fatty  tissue  is  reduced,  and  the  muscles 


REVIEW   OF  LITERATURE.  29 

pale.  Locoed  sheep  may  be  fed  and  fattened  for  mutton,  but 
never  fully  recover  from  the  disease. 

In  the  report  of  Chesnut  and  Wilcox  on  stock-poisoning  plants 
of  Montana,  in  1901,  is  a  discussion  much  like  that  in  the  preceding 
paragraph.  They  state  that  the  most  reliable  observations  on  the 
subject  of  loco  disease  indicate  that  it  is  the  result  of  eating  undue 
quantities  of  certain  weeds,  and  express  the  belief  that  the  plants 
contain  a  poisonous  principle  which  is  harmful  to  domestic  animals. 
They  report  two  experiments,  feeding  a  Belgian  hare  and  a  sheep 
with  extract  of  loco,  but  without  results  except  slight  narcotic 
effects  in  the  rabbit. 

In  1901  Mr.  Maiden  repeats  the  statements  made  in  1897  in  the 

Report  of  the  Department  of  Agriculture  of  Sydney,  and  a-dds  that 

in  all  probability  the  "nenta  disease"  of  South  Africa  is  identical 

-with  the  "pea-eating  disease"  of  Australia  and  the  loco  disease  of 

the  United  States. 

In  the  report  of  the  Oklahoma  Agricultural  Experiment  Station 
-<of  1902  are  some  brief  statements  in  regard  to  loco.  Loco  is  dis- 
tributed over  the  western  half  of  the  territory  and  causes  considerable 
loss. 

In  the  Proceedings  of  the  Pacific  Northwest  Wool  Growers'  Asso- 
ciation of  1902,  Professor  Blankinship  tells  briefly  about  the  effects 
of  eating  Oxytropis  lamberti  and  gives  its  distribution  in  Montana. 
He  states  particularly  that  the  loco  habit  is  taught  to  one  animal 
by  another.  Hence,  he  says,  it  is  very  important  that  animals 
that  have  commenced  to  eat  the  weed  should  be  separated  from 
the  rest  of  the  herd. 

T.  N.  Willing,  in  the  Annual  Report  of  the  Department  of  Agri- 
culture of  the  Northwest  Territories  in  1902,  gives  a  cut  of  Astra- 
galus lamberti  and  says  that  A.  lamberti  and  A.  splendcns  are  abun- 
dant from  Manitoba  to  the  Rockies.  He  gives  a  short  description  of 
the  symptoms  of  loco  poisoning.  Cattle  are  seldom  affected. 

In  1903  Professor  Blankinship,  in  a  bulletin  of  the  Montana  Agri- 
cultural Experiment  Station  on  loco  and  some  other  poisonous 
plants,  treats  rather  fully  of  loco  in  Montana.  He  states  that  the 
loco  plant  in  Montana  is  the  Oxytropis  Idmberii  Pursli.,  or  Astraga- 
lus spicatus  (Hook.)  Rydb.  Aftor  referring  to  the  distribution  of 
the  plant  generally,  ho  says  that  in  Montana  it  is  found  up  to  an 
altitude  of  8,000  feet  in  the  country  east  of  the  Continental  Divide, 
between  Livingston  on  the  west  and  Billings  on  the  east,  the  moun- 
tains on  the  south,  and  north  to  the  vicinity  of  the  Little  Belt  and 
Highwood  Mountains.  Sheep  are  the  principal  sufferers  from  loco 
in  Montana,  horses  and  cattle  boing  rarely  affected,  and  it  is  the 
young  sheep  and  colts  that  are  affected  rather  than  the  older  ones. 


30  THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 

He  then  describes  the  symptoms  of  the  disease,  and,  taking  up  the 
subject  of  prevention,  reasons  that  because  it  is  the  younger  animals 
that  are  principally  affected,  especial  care  should  be  taken  of  them. 
In  regard  to  the  extermination  of  the  plant,  he  says  it  is  possible  to 
accomplish  this  by  digging  it  out,  as  has  been  proved  in  one  or  two 
specific  cases.  This  should  be  done  when  the  plant  is  in  bloom  in 
order  to  kill  the  seed  crop. 

In  1903,  Van  Es  and  Waldron,  of  the  North  Dakota  Experiment 
Station,  in  an  article  entitled  "Some  Stock  Poisoning  Plants  of  North 
Dakota,"  give  a  general  description  of  the  symptoms  of  loco  poison- 
ing which  adds  nothing  to  that  of  previous  publications.  They  state 
that  the  loco  plants  are  Aragallus  lamberti  and  AragaUus  splendens,  the 
former  being  generally  distributed  in  the  State,  while  the  latter  occurs 
on  more  sterile  soil  and  is  reported  only  from  a  few  counties  of  the 
State.  Neither  plant  has  caused  any  large  amount  of  damage  in 
North  Dakota. 

In- 1904  Sayre  published  two  papers.  In  the  first,  entitled  "What 
is  Insanity  in  Lower  Animals?"  he  suggests  that  the  symptoms  of 
loco  disease  may  be  due  to  anemia,  cerebral  congestion,  inflammation 
of  the  brain  or  its  membranes  or  of  the  membranes  enveloping  the 
spinal  cord,  or  to  forage  poisoning.  In  his  second  paper,  published 
in  the  Journal  of  the  Kansas  Medical  Society,  he  gives  an  analysis 
to  determine  the  food  value  of  the  loco  plant,  but  does  not  discuss 
the  results  of  the  analysis.  In  this  paper  he  broaches  as  theories  to 
explain  the  effect  of  loco,  (1)  irritation  by  hairs;  (2)  disturbance  to 
digestion,  such  as  might  happen  from  any  food  in  a  weakened  condi- 
tion of  the  animals  in  spring;  and  (3)  a.  poison  developed  in  the 
process  of  digestion. 

In  1904  J.  E.  Payne,  of  the  Agricultural  Experiment  Station  of 
Colorado,  in  a  report  on  cattle  raising  on  the  plains,  states  that  there 
is  no  evidence  that  cattle  eat  largely  of  the  loco  weed  or  are  affected 
by  it.  Where  these  plants  are  prevalent  the  range  is  very  poor.  He 
further  says  that  the  talk  about  loco  is  kept  up  by  cattle  owners  to 
keep  out  settlers.  A  number  of  unnamed  diseases  may  be  included 
under  the  term  "loco." 

In  1904  Doctor  Marshall  published  in  the  Johns  Hopkins  Hospital 
Bulletin  a  resume  of  the  results  of  his  work  of  the  preceding  two 
years,  while  in  the  service  of  the  United  States  Department  of  Agri- 
culture, in  feeding  locoed  sheep  in  Montana.  His  conclusions  may 
be  summarized  as  follows:  The  loco  disease  affects  horses  and  sheep, 
and  occasionally  cattle  and  goats.  Astragalus  moUissimus  and  Ara- 
gaUus spicatus  are  the  commonest  loco  weeds.  Ranchers  consider  as 
important  accessory  factors:  (1)  Age;  the  disease  appears  before  the 
end  of  the  second  year;  (2)  insufficient  feed;  (3)  insufficient  supply 


REVIEW   OF   LITERATURE.  31 

of  water;  lack  of  salt;  (4)  general  conditions  of  health;  healthy 
animals  never  acquire  the  disease.  He  then  describes  the  symptoms. 

In  this  investigation  only  sheep  were  examined;  all  were  lambs  or 
yearlings.  They  did  not  prefer  the  loco.  Many  had  bronchitis,  con- 
junctivitis, etc.  Usually  the  fleece  was  rough.  All  were  infected 
with  parasites.  The  parasites  found  were  Thysanosoma  actinioides, 
flaemonchus  sp.  (in  the  fourth  stomach),  Metastrongylus  flaria  (in 
the  bronchioles),  Sarcocystis  tenella  (in  the  muscles),  and  Oysticercus 
tenuicollis  (in  the  peritoneal  cavity).  The  fringed  tapeworm  was  so 
abundant  as  to  dilate  the  bile  ducts. 

He  concludes  that  there  is  no  true  loco  disease  of  sheep  produced 
by  the  weed,  but  that  the  so-called  locoed  animals  suffer  from  bad 
feeding,  insuflicient  care,  and  a  variety  of  other  diseases,  the  most 
important  of  which  are  the  parasitic  diseases. 

Fletcher  in  1905,  in  evidence  given  before  the  committee  on  agri- 
culture and  colonization  at  Ottawa,  Canada,  stated  that  the  loco 
weeds  were  abundant  in  Alberta  and  through  to  Manitoba,  but  are 
not  as  injurious  as  in  Montana.  He  has  never  seen  a  case  of  loco 
disease  in  Canadian-bred  animals. 

In  1905  Professor  Linfield,  director  of  the  Agricultural  Experiment 
Station  of  Montana,  in  a  report  of  a  series  of  experiments  on  sheep 
feeding,  compares  the  effect  of  feeding  upon  a  flock  of  locoed  sheep 
with  the  effect  produced  upon  a  flock  of  normal  sheep.  He  states  as 
his  general  results  that  the  locoed  sheep  gained  about  as  much  as  the 
normal  sheep,  but  inasmuch  as  they  were  very  thin  at  the  start,  it 
took  about  twice  as  long  to  get  them  ready  for  market.  All  these 
locoed  sheep  were  treated  with  a  vermifuge  at  the  beginning  of  the 
experiment,  and  the  author  implies  that  their  locoed  condition  may 
have  been  the  combined  result  of  poor  feed  and  parasites.  His  work 
may  be  criticized,  inasmuch  as  his  figures  as  to  gain  in  weight  are 
based  on  the  surviving  locoed  animals.  He  started  with  42,  and  only 
29  remained  at  the  end  of  the  experiment.  lie  states  that  nearly 
half  of  this  lot  was  lost  through  natural  death  or  by  killing  for  post- 
mortem examinations.  The  fact,  however,  remains  that  his  figures 
are  based  on  the  best  of  the  flock,  and  the  statistical  results  of  the 
feeding  experiment  would  probably  not  have  appeared  as  favorable 
for  the  locoed  animals  if  the  whole  number  hail  been  considered. 

Again,  in  1905,  in  the  Proceedings  of  the  Kansas  Academy  of 
Sciences,  Sayro  published  a  partial  bibliography  of  the  subject  and 
repeated  the  report  of  the  analysis  and  his  theory  of  the  causation  of 
the  disease  by  irritation  by  the  hairs  of  the  plant. 

Prof.  L.  G.  Carpenter,  director  of  the  Agricultural  Experiment 
Station  of  Colorado,  in  the  eighteenth  annual  report  of  the  station 
(for  1904-5)  states  that  considerable  work  has  been  done  by  Payne 


32 


THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 


on  the  subject  of  loco,  which  has  made  clear  the  necessary  conditions 
of  the  experiment.  He  also  refers  to  the  cooperative  work  undertaken 
with  the  United  States  Department  of  Agriculture. 

In  this  same  publication  Dr.  George  H.  Glover,  veterinarian  of  the 
Colorado  Agricultural  Experiment  Station,  gives  a  partial  report  upon 
the  first  year's  cooperative  work  at  Hugo. 

Prof.  S.  B.  Nelson  in  1906  reports  feeding  small  quantities  of 
Astragalus  spaldingii,  A.  arrectus,  A.  pursMi,  and  A.  reventus,  but 
with  no  results.  He  suggests  that  longer  feeding  might  have  produced 
more  positive  results. 

Prof.  L.  G.  Carpenter,  in  the  report  of  the  Colorado  Agricultural 
Experiment  Station  for  1906,  published  in  1907,  gives  a  resume  of  the 
work  done  by  the  United  States  Department  of  Agriculture  at  Hugo. 

Doctor  Glover,  in  a  report  of  the  veterinarian  to  the  director  of  the 
Colorado  Experiment  Station,  published  in  1907,  makes  a  brief  state- 
ment also  in  regard  to  the  work  at  Hugo. 

SYMPTOMS  MENTIONED    IN   LITERATURE. 

In  the  preceding  pages  we  find  noted  a  very  large  number  of 
symptoms  of  loco  poisoning.  The  list  below  gives  most  of  these, 
omitting  those  found  by  Doctor  Gee  in  his  experiment  on  his  class, 
as  they  were  almost  infinite  in  number  as  well  as  contradictory.  In 
this  list  the  symptoms  are  arranged  purposely  in  such  a  manner  as  to 
show  their  contradictory  character. 


Congestion  of  abdomen. 

Abortion. 

Anemia. 

Loss  of  appetite. 

Arteries  gorged  with  thick,  dark  blood. 

Bile  thin  and  watery. 

Bladder  with  inner  coat  softened. 

Bladder  distended. 

Blindness. 

Body  cavities  with  an  excess  of  serous 
fluid. 

Brain  atrophied. 

Brain  bloodless. 

Brain  with  the  membranes  inflamed. 

Brain  congested. 

Pia  mater  injected. 

Gray  tissue  of  brain  darker  than 
normal. 

Gray  substance  of  brain  red  and 
edema  tous. 

Brain  tissues  soft  and  pulpy. 

Sinuses  of  brain  filled  with  fluid. 

Lateral  ventricles  of  brain  holding 
serous  effusion. 


Fourth  ventricle  of  brain  with  blood 
clot. 

Breathing  short. 

Coat  rough. 

Winter  coat  retained. 

Constipation. 

Diarrhea. 

Convulsions. 

Craziness. 

Hallucinations. 

Lack  of  muscular  coordination. 

Emaciation . 

Exostosis  of  frontal  bone. 

Eyes  glassy. 

Eyes  dull  and  staring. 

Pupils  dilated. 

Vision  impaired. 

High  temperature. 

Low  temperature. 

Frothing  at  the  mouth. 

Shaking  head. 

Impaired  hearing. 

Heart  of  increased  size. 

Heart  with  inflamed  valves. 


SYMPTOMS    AND    REMEDIES. 


33 


Heart  bloodless. 

Heart  with  reduced  action. 

High  stepping. 

Hyperesthesia. 

Intestines  filled  with  gases. 

Intestines  congested. 

Intestines  green. 

Intestines  with  tissues  degenerated. 

Kidneys  congested. 

Purkinje's  cells  in  kidneys  lacking. 

Difficult  to  lead. 

Liver  dense. 

Liver  small. 

Liver  enlarged. 

Lungs  bloodless. 

Narcotized. 

Stiff  neck. 

Irritability  of  motor  nerves. 

Decrease  of  irritability  in  sensory 
nerves. 

General  derangement  of  nervous 
system. 

Paralysis  of  mouth  or  tongue. 

Paralysis  of  hind  legs. 

Omentum  inflamed,  with  tumors. 


Rearing  and  plunging. 

Shying. 

Solitary  habit. 

Spinal  cord  edematous. 

Spinal  cord  membranes  inflamed  and 
adherent. 

Spleen  small. 

Excitement  followed  by  depression. 

Stomach  ruptured. 

Third  stomach  (psalterium)  softened. 

Second  stomach  (reticulum)  softened. 

First  stomach  (rumen)  lining  worn, 
ulcerated,  and  decomposed. 

Swelling  under  the  jaw. 

Swelling  of  dependent  parts  of  body. 

Te'eth  loose. 

Teeth  not  loose. 

Tremors. 

Tendency  to  turn  either  to  the  right  or 
to  the  left  but  not  in  both  directions. 

Urine  offensive. 

Vomiting. 

Weakness  across  loins. 

Weakness  and  staggering  gait. 


While  this  list  is  confusing  because  of  the  number  of  items  and  the 
contradictions  involved,  yet  in  regard  to  some  of  the  symptoms  there 
is  great  uniformity.  The  following  symptoms  have  been  noted  by  a 
large  number  of  observers,  and  in  regard  to  them  there  is  a  fairly 
general  agreement: 


Slow,  staggering  gait. 
Rough  coat. 
Staring  look. 
Emaciation. 


Lack  of  muscular  coordination. 
Extreme  nervousness,  shown  in  shying, 
rearing,  etc. 


REMEDIES    PROPOSED. 

The  remedies  suggested  for  the  loco  disease  by  different  writers,  as 
would  be  expected  from  the  indefinite  knowledge  of  the  subject,  have 
been  of  various  kinds,  many  of  them  having  no  logical  basis.  Among 
them  are  the  following: 

1.  Potassic  bromifl,  belladonna,  and  bleeding. 

2.  Amputation  of  the  tail,  which,  of  course,  i«  simply  one  form  of  bleeding. 

It.  Potassium  iodid  and  qiiinin,  with  strychnin;  in  some  cases  it  may  be  desirable 
to  add  jaboiundi  or  pilocarpin. 

4.  It  lister  on  the  top  of  the  head  with  the  administration  of  GO  grains  of  calomel 
every  second  or  third  night.     The  calomel  should  be  followed  by  sulphate  of  iron. 

5.  A  prescription  of  belladonna,  calomel,  licorice,  and  glycerin. 

6.  A   prescription  of  iron  sulphate,  gentian,   muriate  of  ammonia,  and  potassic 
nitrat<>. 

79154-Bull.  112—09 3 


34  THE    LOCO-WEED   DISEASE   OF   THE    PLAINS. 

7.  In  acute  cases,  permanganate  of  potash,  sulphate  of  ammonia,  morphine  as  an 
antispasmodic.     In  chronic  cases,  remedies  to  affect  the  stomach,  as  common  salt, 
hydrochloric  acid,  and  gentian  root. 

8.  Muriate  tincture  of  iron  with  hygienic  accessories. 

CONCLUSIONS    FROM    LITERATURE. 

From  the  foregoing  review  of  the  literature  we  may  deduce  the 
following  conclusions: 

1.  There  is  a  disease  common  among  horses,  cattle,  and  sheep  in 
the  semiarid  region  of  the  West,  the  animals  affected  showing  these 
characteristics:  Slow,   staggering  gait,  rough  coat,   staring,   vacant 
look,  and  emaciation.     They  have  hallucinations,  can  not  be  led  or 
backed,  show  more  or  less  lack  of  muscular  coordination,  gradually 
lose  flesh,  and  die.     They  show  a  hypersensitive  condition  of  the 
nerves,  so  that  if  a  horse  affected  with  loco  disease  is  suddenly  startled 
he  may  rear  and  fall  over  backward.     Cattle  show  less  pronounced 
symptoms,  but  in  general   are  affected   like  the  horses.     The  char- 
acteristic of  a  locoed  steer  is  the  shaking  head,  together  with  the 
other  nervous  phenomena.     To  these  symptoms  may  be  added  some 
others  upon  which  there  is  no  general  agreement. 

2.  The  cause  of  this  disease  is  quite  uniformly  ascribed  by  the 
stockmen  to  plants  known  by  them  as  loco  plants,  of  which  the  prin- 
cipal ones  are  Astragalus  mollissimus  and  Aragallus  lamberti.     Similar 
properties  are  ascribed  to  other  closely  allied  species  in  Montana, 
Wyoming,  Arizona,  and  California. 

3.  Scientific  investigations  of  the  subject  have  led  to  very  contra- 
dictory results. 

It  will  be  noticed  from  the  review  of  the  literature  that  in  the 
chemical  and  pharmacological  examination  Prescott  got  no  positive 
results.  The  same  is  true  of  the  experiments  made  by  Gee.  Ken- 
nedy found  no  poisonous  principle  and  fed  the  loco  to  a  dog  with  no 
results.  Day  got  from  the  extract  fed  to  cats  definite  loco  symp- 
toms, and  similar  results  from  her  experiment  with  a  jack  rabbit. 
The  work  of  Power  and  Cambier  led  to  only  negative  results.  Sayre 
made  numerous  experiments  on  himself  and  animals,  and  has  reached 
the  general  conclusion  that  the  weed  possesses  no  poison.  It  will  be 
seen  that  the  only  positive  proof  of  the  poisonous  character  of  the 
plant  was  obtained  by  Doctor  Day.  The  preponderance  of  laboratory 
tests  made  up  to  the  time  that  the  Bureau  of  Plant  Industry  under- 
took its  investigations  was,  therefore,  against  the  poisonous  character 
of  the  plant. 

The  results  of  the  study  of  locoed  cattle,  horses,  and  sheep  in  the 
field  are  no  more  conclusive.  .  The  reports  of  post-mortems  show 
few  lesions  common  to  all  cases,  or  even  to  any  considerable  number 
of  them.  There  is  a  fairly  general  agreement  as  to  some  abnormal 


CONCLUSIONS  FROM   LITERATURE.  35 

condition  of  the  brain  and  the  nervous  system,  but  so  far  as  the  other 
organs  of  the  body  are  concerned,  the  reports  do  not  agree  with  each 
other.  There  seems  to  be  a  general  feeling  of  skepticism  among 
those  who  have  seen  cases  in  the  field  as  to  the  actual  poisonous 
properties  of  the  plants.  The  following  have  been  suggested .  as  the 
possible  causes  of  the  disease: 

1.  Starvation. 

2.  Irritation  of  the  stomach  by  the  hairs  of  the  leaves. 

3.  Penetration  of  the*  stomach  by  the  sharp  hooks  of  the  seed  pods. 

4.  The  loco  absorbs  the  juices  of  the  stomach,  collects  as  a  dry  mass,  causes  pressure 
upon  the  circulation,  and  finally  death. 

5.  The  formation  of  balls  in  the  stomach  from  sand  taken  in  when  the  grass  is  short 
(bezoars),  and  the  consequent  irritation  and  inflammation  due  to  the  presence  of  this 
foreign  substance. 

6.  Impaction  of  the  intestines  by  twigs,  etc. 

7.  Fermentation  of  the  materials  in  the  stomach. 

8.  Tapeworms. 

9.  Other  parasitic  worms. 

10.  Eggs  or  bots. 

11.  Trypanosomes. 

12.  Some  poisonous  principle  in  the  plants. 

To  these  possible  causes  might  be  added  some  suggestions  made  by 
stockmen  which  have  little  foundation.  It  is  generally  known  that 
the  loco  plants  are  attacked  by  a  considerable  number  of  insect 
enemies,  of  which  more  will  be  said  later.  Among  them  are  certain 
insects  whose  larvae  live  in  the  roots  and  stems  of  the  plants  and  have 
been  noticed  for  a  great  many  years  by  the  stockmen.  Many  of  the 
stockmen  consider  that  these  "worms,"  as  they  call  them,  are  con- 
nected directly  or  indirectly  with  the  loco  disease.  Some  of  them  state 
that  the  eggs  of  the  worms  are  taken  into  the  body  of  the  animal,  hatch 
out  there,  and  live  in  the  alimentary  canal; evidently  confounding  the 
ordinary  parasitic  worms  of  animals  with  these  insect  larviv.  ('.  1). 
Steele,  in  Farm  and  Ranch,  in  1901,  suggests  that  these  "worms" 
consume  the  food  in  the  stomach  and  thus  produce  starvation.  One 
correspondent  of  our  ofliee  has  elaborated  an  interesting  theory  to 
this  effect:  That  the  cattle  and  horses  eat  the  loco  plants  upon  which 
are  the  worms,  as  he  calls  them,  and  the  eggs  of  the  worms.  These 
eggs  hatch  out  in  the  stomach  of  the  locoed  animal  and  crave  loco  for 
their  own  food,  and  it  is  to  supply  food  to  satisfy  this  craving  of  t he- 
worms  that  the  horse  or  the  steer  frantically  seeks  loco. 

It  will  bo  remembered  that  Sayre  in  his  1904  paper  broaches  three 
distinct  theories:  (1)  Irritation  by  hairs;  (2)  disturbance  of  diges- 
tion, such  as  might  have  been  caused  by  any  food  in  the  weakened 
condition  of  the  animals  in  the  spring;  and  (3)  a  poison  developed  in 
the  process  of  digestion. 

Marshall's  investigations  led  him  to  conclude  that  the  loco  plant 
was  not  the  direct  cause  of  the  disease  and  that  many  cases  of  so- 


36 


THE    LOCO-WEED   DISEASE    OF    THE    PLAINS. 


called  loco  disease  were  really  caused  by  animal  parasites.  This 
seemed  particularly  probable  in  the  case  of  sheep,  which  all  through 
our  western  region  are  infested  with  (Estrus  ovis  and  with  TJiysa- 
nosoma  actinioides,  as  well  as  certain  other  animal  parasites. 

It  will  be  seen  that  the  loco  problem  up  to  the  time  when  the  re- 
view of  this  literature  closed  was  an  open  one,  with  the  presumption 
in  faAror  of  the  nonpoisonous  character  of  the  plant,  and  in  taking 
up  the  investigation  of  this  subject  it  seemed  necessary  as  the  first 
step  to  determine  positively  whether  the  loco  plants  were  really  the 
cause  of  the  so-called  loco  disease. 


PLANTS  KNOWN  AS  LOCO  PLANTS. 

A  large  number  of  plants  have  been  known  as  loco  plants.  The 
following  list  is  taken  from  the  literature  on  the  subject.  It  is  to 
be  presumed  that  there  have  been  some  errors  in  determination, 
but  the  length  of  the  list  shows  that  loco  is  a  term  which  has  been 
applied  quite  widely.  By  general  agreement,  however,  the  term, 
outside  of  California,  New  Mexico,  and  Arizona,  is  now  rather  gen- 
erally confined  to  the  two  species,  Aragallus  lamberti  and  Astragalus 
mollissimus.  In  some  localities  the  term  "loco"  is  confined  to  Astra- 
galus mollissimus,  but  this  is  generally  in  places  where  Aragallus 
lamberti  is  comparatively  rare. 


LIST    OF    SPECIES. 


Amarantus  albus. 
Astragalus  bigelovii  Gray. 
Astragalus  crolalaria. 

(=A.  oocarpus  Gray.) 
Astragalus  dorycnioides. 

(=A.  succumbens  Dougl.) 
Astragalus  hornii,  A.  Gray. 
Astragalus  lotijlorus  Hook. 
Astragalus  lentiginosus  Dougl. 
Astragalus  menziesii  Gray. 
Astragalus  mollissimus  Torr. 
Astragalus  mortoni  Nutt. 
Astragalus  palousensis  Piper. 
Astragalus  spaldingii  Gray. 
Astragalus  tridaclylicus  A.  Gray. 
Aragallus  lamberti  (Pursh.)  Greene. 
Aragallus  sericeus  (Nutt.)  Greene. 
Aragallus  spicatus  (Hook.)  Rydb. 
Argemone  mexicana  L. 
Cannabis  saliva  L. 


Crolalaria. 

Cystium  diphysum  (A.  Gray)  Rydb. 

Datura  stramonium  L.      . 

Diholcos  bisulcatus  (Hook.)  Rydb. 

Diholcos  haydenianus  (A.  Gray)  Rydb. 

Fritillaria  pudica  Spreng. 

Lathyrus  polymorphus  Nutt. 

(=L.  incanus.) 
Leucocrinum  montanum  Nutt. 
Malvastrum  coccineum  (Pursh.)  Gray. 
Oxybaphrus. 
Oxytropis  lagopus  Nutt. 

(= Aragallus  lagopus  Nutt.) 
Physostigma  venosum. 
Psoralea  cuspidata  Pursh. 
Khamnus  lanceolata  Pursh. 
Sophora  sericea  Nutt. 
Stipa  viridula  Triv. 
Zygadenus  elegans  Pursh. 

(=Anticlea  elegans  (Pursh.)  Rydb. 


DESCRIPTION   OF   LOCO   PLANTS. 


37 


DESCRIPTION    OF    ARAGALLUS    LAMBERTI. 

AragaUus  lamberti  (PI.  I)  is  a  perennial  growing  from  a  root 
which  may  extend  2  or  3  feet  or  more  into  the  ground.  It  is  acau- 
lescent  and  the  leaves  rise  to  a  height  of  a  foot  or  more.  The  general 
habit  of  the  plant  is  of  erectness.  The  leaflets  are  oblong,  lanceolate, 
or  linear,  and  are  covered  with  a  variable  amount  of  silky  hairs. 
In  some  varieties  this  pubescence  is  quite  dense.  The  flower  scapes 
are  longer  than  the  leaves  and  bear  spikes  which  are  either  densely 
or  sparsely  flowered.  The  flowers  are  large  and  variable  in  color; 
the  more  common  color  of  the  plants  on  the  plains  is  white,  but  they 
may  be  distinctly  purple.  The  variations  are  from  white,  through  a 
light  purple  and  lilac,  to  a  distinct  purple.  In  some  cases  the  corolla 


FIG.  1.— Distribution  of  Aragallus  lumberti  in  the  United  States. 

is  white  and  the  calyx  red.  In  the  mountain  varieties  there  is  the 
same  variability  in  color,  but  the  darker  ones  are  more  common,  the 
predominating  colors  being  deep  violets  and  purples.  The  white 
varieties  are  commonly  found  in  woods  and  near  streams. 

The  plants  are  strikingly  beautiful,  and  grow  so  abundantly  that 
when  in  blossom  on  the  plains  largo  areas  are  as  white  as  a  field  cov- 
ered with  snow,  while  in  the  mountains,  although  lass  abundant,  the 
patches  of  several  acres  of  bright  purple  and  violet  flowers  are 
extremely  attractive.  The  pods  of  the  Aragattus  lamberti  are  rather 
long,  pubescent,  and  indistinctly  two-celled.  It  grows  most  abun- 
dantly on  the  low  hills  of  the  plains,  and  in  the  pastures  at  the  base 
of  the  mountains  up  to  a  height  of  perhaps  9,000  feet.  It  prefers  a 
sandy  soil. 

AragdUus  lamberti  has  an  extremely  wide  range,  as  may  bo  soon 
from  figure  1.  It  is  found  from  Alaska  on  (ho.  north  down  through 


38  THE   LOCO- WEED   DISEASE   OF   THE   PLAINS. 

the  Dakotas  and  as  far  east  as  central  Minnesota;  in  Montana,  Wyo- 
ming, western  Nebraska  and  Kansas,  eastern  Colorado,  Oklahoma, 
western  Texas,  New  Mexico,  and  Arizona.  In  all  these  localities 
more  or  less  damage  has  been  reported,  but  it  is  in  Wyoming,  Colo- 
rado, and  Arizona  that  the  most  trouble  has  occurred.  It  is  abun- 
dant in  the  eastern  foothills  in  Colorado,  and  on  many  of  the  moun- 
tain ranges  horses  are  no  longer  turned  out.  It  is  especially  abundant 
in  parts  of  Elbert,  Lincoln,  and  Cheyenne  counties  in  eastern  Colo- 
rado. In  Arizona  there  is  a  large  amount  of  this  plant  about  the  base 
of  the  San  Francisco  Mountains.  It  grows  more  abundantly  east  of 
the  Continental  Divide,  but  is  by  no  means  confined  to  this  region. 
Considerable  patches  of  it  are  found  on  the  western  slope  in  Colorado. 
In  this  region  it  has  so  far  done  very  little  damage,  and  most  of  the 
stockmen  do  not  know  that  it  occurs  in  that  region  at  all. 

The  plant  belongs  to  the  semiarid  region.  It  is  not,  however, 
entirely  confined  to  dry  soils  and  sterile  regions.  In  the  Black  Hills 
of  South  Dakota  it  occurs  in  the  forests  and  in  soil  which,  during  a 
part  of  the  year  at  least,  is  full  of  moisture.  The  pubescence  is  much 
more  marked  in  the  dry  regions.  Aragallus  lamberti  is  popularly 
known  as  "rattleweed"  or  "white  loco." 

The  species  spicatus  (Hook)  Rydb.,  albiftorus  Nelson,  and  sericeus 
Gray  are  considered  by  Prof.  C.  F.  Wheeler,  who  has  determined  our 
plants,  as  identical  with  lamberti. 

DESCRIPTION    OF    ASTRAGALUS    MOLLISSIMUS. 

Astragalus  mollissimus  (PI.  II)  is  a  perennial  growing  from  a  long 
root  like  that  of  Aragallus  lamberti.  Unlike  the  latter,  it  has  distinct 
stems  in  the  older  plants,  although  the  young  plants  appear  acaules- 
cent.  The  plant  is  inclined  to  be  decumbent,  although  young  plants 
are  sometimes  quite  erect.  In  this  habit  it  differs  markedly  from 
Aragallus  lamberti.  Most  of  the  plants  are  comparatively  small, 
living  apparently  not  more  than  two  or  three  years.  Under  favor- 
able circumstances,  however,  they  may  grow  into  large  bushy  struc- 
tures, perhaps  a  foot  high  and  from  1  to  2  feet  in  diameter.  The 
leaflets  are  broadly  ovate  or  elliptical,  and  densely  pubescent.  This 
pubescence  is  very  much  greater  than  in  Aragallus  lamberti.  The 
flower  scapes  do  not  ordinarily  much  exceed  in  length  the  leaves,  and 
bear  rather  dense  spikes  of  deep  violet  or  purple  flowers.  The 
flowers  are  much  smaller  than  those  of  Aragallus  lamberti  and  less 
showy.  The  pods  are  thicker  than  those  of  Aragallus  lamberti, 
smooth,  and  distinctly  two-celled. 

Plate  II,  figure  1,  shows  the  appearance  of  the  younger  plants  and 
the  characteristic  appearance  of  the  leaves,  flowers,  and  fruit,  while 
figure  2  of  that  plate  shows  the  general  appearance  of  the  older 


BUL.  112,  BUREAU  OF  AMMAL  INDUSTRY,   U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  I. 


BUL.  112,  BUREAU  OF  ANIMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  II. 


Fig.  1. — Flower  and  fruit. 


Fin.  2.     Habit  of  plant. 
PURPLE  OR  WOOLLY  LOCO  (ASTRAGALUS  MOLLISSIMUS' 


DISPERSAL   OF   LOCO   PLANTS. 


39 


plants,  in  which  the  decumbent  character  is  more  pronounced.  It 
does  not  grow  in  as  great  abundance  as  the  rattleweed,  although  occa- 
sionally a  few  acres  may  be  pretty  well  covered.  It  grows  best  on  an 
adobe  soil,  and  where  the  two  species — AragaUus  lamberti  and  Astra- 
galus moUissimus — grow  near  together,  Astragalus  moUissimus  occupies 
the  depressions  and  AragaUus  lamberti  is  found  on  the  hills. 

Its  range  (see  fig.  2)  is  not  so  wide  as  that  of  AragaUus  lamberti.  It 
occurs  in  Wyoming,  Nebraska,  Kansas,  Colorado,  Oklahoma,  Texas, 
New  Mexico,  and  Arizona.  In  the  eastern  part  of  the  plains  region 
of  Colorado  and  in  western  Kansas  and  Nebraska  Astragalus  moUis- 
simus is  very  abundant,  while  AragaUus  lamberti  is  comparatively 
rare.  The  same  is  true  of  the  Panhandle  in  Texas.  In  parts  of  New 


FIG.  2. — Distribution  of  Antragalu*  moUissimus  in  the  United  States. 

Mexico  it  grows  very  luxuriantly.  This  is  particularly  true  in  some 
portions  of  the  Estancia  Valley  and  in  the  regions  about  Santa  Rosa. 
It  is  found  in  less  abundance  in  Arizona,  and  apparently  in  that  Terri- 
tory does  very  little  harm.  The  most  harmful  of  the  loco  plants  in 
Arizona  appear  to  be  entirely  distinct  from  the  two  species  under 
discussion. 

Astragalus  mottissimus  is  popularly  known  as  "purple  loco," 
"woolly  loco,"  or  "Texas  loco."  Sometimes  it  is  spoken  of  by  the 
ranchmen  as  "the  loco." 

DISPERSAL   OF   ARAGALLUS    LAMBKKTI    AND    ASTRAGALUS   MOLLISSIMU8. 

When  AragaUus  lamberti  ripens,  the  pods  open  while  still  on  the 
flower  scapes  and  the  seed  is  scattered  in  the  immediate  neighbor- 
hood of  the  plant.  The  pods  of  Astragalus  moUissimiu  are  heavier 


40  THE    LOCO-WEED  DISEASE   OF   THE   PLAINS. 

and  may  lie  upon  the  ground,  but  because  of  their  weight  are  not 
moved  to  any  extent  by  the  winds.  Neither  of  these  plants  breaks 
off  and  becomes  scattered  in  tumbleweed  fashion.  It  follows  that  in 
the  case  of  both  of  these  species  most  of  the  new  plants  spring  up  in 
the  immediate  neighborhood  of  the  parent  plant,  and  the  dispersal  of 
the  plants  is  a  comparatively  slow  matter.  It  should  not  be  assumed 
that  the  wind  has  no  influence  in  scattering  the  seeds,  for  in  a  countiy 
of  violent  wind,  seed,  like  everything  else  that  is  loose,  will  be  carried 
about  more  or  less.  This  is  shown  in  the  fact  that  Astragalus  mollis- 
simus  is  frequently  abundant  in  and  near  wagon  roads,  doubtless 
because  the  moving  seeds  have  been  arrested  hi  the  depressions. 
Loco  is  said  to  be  especially  abundant  near  old  sheep  trails.  This 
may  be  partly  because  of  the  seeds  carried  in  the  droppings  of  the 
sheep  and  partly  because  of  the  arrest  of  the  moving  seeds  by  the 
depressions  and  the  planting  of  these  seeds  by  the  feet  of  the  sheep. 
It  is  said  by  some  (Blankinship,  1903)  that  the  bison  were  instru- 
mental in  the  distribution  of  the  plants  either  through  their  drop- 
pings or  because  of  their  habits  of  wallowing,  by  reason  of  which  they 
may  have  carried  the  seed  to  great  distances.  These  statements  in 
regard  to  the  distribution  by  sheep  and  bison,  however,  are  entirely 
theoretical,  for  no  exact  observations  have  been  made. 

RELATIONS    OF    LOCO    PLANTS    TO    FERTILE    SOIL. 

Incidentally  it  may  be  remarked  that  the  loco  weeds,  like  other 
leguminous  plants,  have  root  tubercles,  and  presumably  are  effica- 
cious in  adding  nitrogen  to  the  soil  content.  Mr.  W.  S.  Pershing,  of 
Limon,  Colo.,  states  that  he  has  noticed  that  he  has  had  especially 
good  crops  when  he  has  used  land  on  which  loco  has  been  growing. 
It  seems  very  possible  that  while  loco  is  a  curse  to  the  stockmen  it 
may  be  of  some  benefit  to  the  farmer. 

EXPERIMENTAL  WORK  LIMITED  TO  TWO  PLANTS. 

The  experimental  work  on  which  this  paper  was  based  was  limited 
to  the  two  species  Astragalus  mollissimus  and  Aragallus  lamberti. 
There  is  reason  to  believe,  however,  that  a  considerable  number  of 
related  plants  may  possess  the  same  properties. 

Horses  in  Arizona  and  New  Mexico  die  with  the  typical  symptoms 
of  loco  poisoning,  and  post-mortem  examinations  show  lesions  simi- 
lar to  those  found  in  the  victims  of  Astragalus  mollissimus  or  Ara- 
gallus lamberti,  but  the  loco  plants  are  different  species  from  those 
found  farther  north.  While  there  is  little  reason  to  doubt  that  these 
plants  possess  the  same  poisonous  principle  and  produce  the  same 
result,  experimental  work  has  not  been  undertaken  to  demonstrate 
these  facts. 


OTHER    PLANTS    PRODUCING    SIMILAR    SYMPTOMS.  41 

Through  many  parts  of  the  West  horses  are  said  to  become  "saged" 
and  to  have  many  of  the  symptoms  of  loco  poisoning.  This  has  been 
noted  by  Mayo.  The  author  has  seen  some  cases  of  so-called  saged 
horses,  but  there  was  no  means  of  proving  that  they  had  not  been 
eating  loco  plants.  The  testimony  of  stockmen  who  have  what 
seems  to  them  clear  evidence  of  the  production  of  these  symptoms 
by  the  sages  is  not  to  be  lightly  set  aside.  It  is  hoped  that  it  may 
be  possible  to  do  some  convincing  experimental  work  on  these  plants. 

Reference  should  be  made,  in  passing,  to  the  poisonous  effects  of 
Swainsona  galegifolia,  known  as  the  Darling  pea  or  indigo  plant, 
and  other  species  of  Swainsona  which  are  said  to  produce  hi  Aus- 
tralia symptoms  like  those  caused  by  the  American  loco  plants. 
MacOwan  considers  the  "nenta"  of  the  Cape  as  produced  in  a 
similar  way. 


PART  II.— EXPERIMENTAL  WORK. 

THE  PROBLEM  TO  BE  SOLVED. 

It  will  be  seen  from  the  foregoing  that  when,  at  the  earnest  and 
persistent  solicitation  of  the  stockmen,  it  was  decided  by  the  Depart- 
ment of  Agriculture  to  make  a  thorough  study  of  the  subject,  there 
was  very  little  definite  knowledge  to  start  upon.  In  spite  of  the 
fact  that  the  subject  had  been  under  investigation  for  a  third  of  a 
century,  there  was  no  consensus  of  opinion  even  in  regard  to  the 
poisonous  or  nonpoisonous  character  of  the  plants  themselves.  The 
stockmen  with  very  few  exceptions  were  convinced  that  the  plants 
were  the  cause  of  the  disease.  On  the  other  hand,  laboratory  in- 
vestigations were  contradictory  and  the  investigations  in  the  field 
were  not  conclusive.  The  problem,  as  presented  to  the  Department 
then,  involved: 

1.  The  definite  determination  of  the  poisonous  or  nonpoisonous 
character  of  the  loco  plants.     This  included   (a)  field  experiments 
in  feeding  animals  under  normal  conditions,  with  proper  controls, 
to  find  out  whether  the  disease  could  be  produced  by  the  loco  plants, 
and  (&)  a  pharmacological  examination  of  the  plants  to  determine 
whether  a  poisonous  principle  could  be  extracted,  and  if  it  could  be 
extracted  to  determine  its   properties.     The   pharmacological  work 
was  entirely  in  the  hands  of  Dr.  Albert  C.  Crawford,  who  has  made 
an  independent  report  of  his  investigations.0 

2.  A  careful  examination  of  locoed  animals,  with  numerous  post- 
mortems to  determine  the  pathological  lesions,  with  the  end  in  view 
of  making  an  accurate  and  fairly  complete  diagnosis  of  the  disease 
from  the  pathological  side. 

3.  An  attempt  to  find  some  remedy  for  the  trouble.     This  branch 
of  the  subject  presented  two  aspects:  (a)  The  suggestion  of  measures 
to  eradicate  the  plant  or  to  reduce  its  numbers,  if  it  was  found  to  be 
the  cause  of  the  disease;  (6)  the  suggestion  of  remedies  which  could 
be  given  to  the  animals  either  for  a  cure  or  for  lessening  the  effects 
of  the  disease. 

It  was  evident  that  the  investigation  would  have  to  be  equipped 
in  a  very  broad  way.  While  the  study  was  primarily  of  the  loco 

a  Bulletin  129,  Bureau  of  Plant  Industry. 
42 


PLAN   OF   EXPERIMENT.  43 

plants,  it  was  necessary  to  be  provided  with  means  of  making  post- 
mortems, giving  special  attention  to  the  presence  of  animal  parasites; 
pathological  tissues,  must  also  be  collected  and  examined,  the  blood 
must  be  studied,  and  an  equipment  for  the  cultivation  of  pathogenic 
bacteria  must  be  on  hand. 

PLAN  OF  WORK. 

To  carry  out  the  first  point  in  the  investigation,  it  was  determined 
to  secure  the  use  of  land  somewhere  in  the  loco  area,  and  fence  in 
one  piece  covered  with  loco  thickly  enough  so  that  the  animals  in 
the  pasture  would  be  compelled  to  eat  loco,  but  with  grass  enough 
so  that  there  would  be  no  question  of  starvation.  Another  piece  of 
ground,  as  nearly  like  the  first  as  possible,  but  free  from  loco,  was  to 
be  used  as  a  control  pasture.  In  addition,  animals  should  be  con- 
fined in  the  corrals  and  fed  on  cut  loco,  cut  loco  and  hay,  etc.  It 
would  be  necessary  also  to  confine  certain  groups  of  animals  to  definite 
loco  species,  and  thus  determine  the  differences,  if  any,  in  their 
poisonous  properties.  Incidentally,  it  was  desired  to  travel  through 
the  loco  country  arid  collect  facts  in  regard  to  the  losses  from  loco, 
the  loco  conditions  in  different  places,  and  the  distribution  of  the 
supposed  poisonous  plants. 

LOCATION  OF  EXPERIMENT. 

As  Colorado  has  perhaps  suffered  more  losses  from  loco  than  any 
other  region  it  was  determined  to  locate  the  experiment  in  that 
State.  A  cooperative  agreement  was  entered  into  with  the  Colo- 
ratio  Agricultural  Experiment  Station  .by  which  the  station  agreed 
to  furnish,  in  aid  of  the  work,  the  stock  to  be  experimented  upon 
and  the  services  of  a  veterinarian  for  consultation  when  called  upon. 
After  some  time  spent  by  Doctor  True  and  the  author  in  examining 
different  areas  of  the  State  where  loco  was  doing  most  harm,  it  was 
decided  to  locate  a  temporary  station  at  Hugo,  in  Lincoln  County. 
The  choice  of  this  location  was  determined,  in  part,  by  the  fact 
that  no  part  of  the  West  has  suffered  more  from  loco  than  this  section 
of  Colorado,  and  in  part  because  of  the  active  interest  in  the  inves- 
tigation manifested  by  the  stockmen  of  that  neighborhood. 

In  this  connection  the  author  makes  grateful  acknowledgment  of 
the  courtesies  extended  and  valuable  assistance  rendered  by  many 
persons,  too  numerous  to  mention  l>y  name,  in  the  course  of  the  inves- 
tigations. The  stockmen  not  only  gave  freely  of  their  time  in  show- 
ing local  conditions,  but  were  always  ready  to  furnish  animals  for 
autopsy  and  to  assist  in  their  examination.  The  county  board  of 
Lincoln  County  made  liberal  appropriations  for  the  experiment. 


44 


THE    LOCO-WEED   DISEASE    OF    THE   PLAINS. 


Special  acknowledgment,  too,  should  be  made  of  the  assistance  very 
freely  given  by  the  railroad  officials  in  the  territory  visited ;  without 
this  help  it  would  have  been  impossible  to  handle  the  work  with  the 
funds  at  our  disposal. 

PRELIMINARY  WORK. 

During  a  preliminary  trip  through  the  State  a  considerable  number 
of  locoed  animals  were  seen.  The  picture  in  the  text  of  case  513 
(fig.  3) ,  a  stunted  colt  seen  near  Wray,  is  typical  of  the  locoed  horses 
observed  on  this  trip.  In  spite  of  many  cases,  where  there  was  an 
abundance  of  feed,  the  conclusion  was  reached  that  in  the  great  ma- 
jority of  cases  starvation  was  the  principal  if  not  the  only  factor  in 
the  so-called  loco  disease.  Prof.  W.  L.  Carlyle,  of  the  Agricultural  Col- 
lege, accompanied  us 
in  our  examination 
of  the  neighborhood 
of  Hugo,  and  agreed 
with  us  that  an  abun- 
dance of  good  feed 
would  greatly  reduce 
the  number  of  cases 
and  perhaps  elimi- 
nate the  problem. 

An  old  ranch  house 
with  its  corrals  was 
secured  as  laboratory 
headquarters  for  the 
work.  A  piece  of 
ground  of  something 
over  200  acres,  where 
the  Aragallus  lamberti  was  especially  thick,  was  prepared  as  a  loco 
pasture  and  was  so  fenced  that  the  animals  should  always  have 
access  to  running  water.  Over  the  whole  of  this  200-acre  pasture  the 
Aragallus  lamberti  was  distributed  in  very  great  abundance.  It  is 
doubtful  if  there  was  a  square  yard  of  the  pasture  which  did  not  have 
one  or  more  of  the  plants.  It  was  also  very  nearly  a  field  of  Ara- 
gallus lamberti  simply.  There  wrere  in  the  depressions  small  patches 
of  Astragalus  mollissimus,  but  during  the  progress  of  the  experiment 
the  animals  were  watched  carefully,  and  there  is  reason  to  think  that 
none  of  them  ate  this  plant  in  this  pasture. 

Another  piece  of  ground  near  by  was  arranged  for  a  control  pas- 
ture. This  piece  of  land  had  a  comparatively  small  amount  of  loco 
upon  it.  A  force  was  set  at  work  to  clear  out  this  pasture  so  that  it 
would  be  to  all  intents  and  purposes  a  loco-free  piece  of  ground. 
During  the  summer  men  were  sent  over  it  two  or  three  times  in  addi- 


FIG.  3.    Case  513.    A  locoed  colt,  stunted  in  its  growth  by  loco 
poisoning. 


THE   FIRST   SEASON'S   WORK.  45 

tion,  in  order  to  kill  out  the  seedlings  as  they  came  up  later  in  the 
season.  Thus  in  this  pasture  we  had  a  piece  of  ground  very  nearly 
like  the  loco  pasture  but  without  the  loco  plants.  Inasmuch,  how- 
ever, as  the  loco-free  pasture  was  somewhat  lower,  it  is  a  fact  that  the 
grass  was  rather  better  than  in  the  loco  pasture.  However,  there 
was  an  abundance  of  grass  in  the  loco  pasture,  so  that  we  consider 
that  the  starvation  element  was  entirely  eliminated. 

WORK    OF    THE    FIRST    SEASON. 

Twelve  steers  and  fifteen  horses  were  received  from  the  agricul- 
tural experiment  station  for  experimental  purposes.  Part  of  these 
arrived  at  the  end  of  April,  1905,  and  part  the  first  week  in  May.  By 
the  end  of  the  first  week  in  May  the  experiment  was  fairly  started. 
The  animals  were  given  individual  brands  and  numbered,  so  that  the 
notes  of  each  animal  could  be  kept  under  its  own  number.  Five  of 
the  cattle,  Nos.  1,  2,  4,  5,  and  6,  and  four  of  the  horses,  Nos.  13,  16, 
22,  and  23,  were  put  in  the  loco-free  pasture  and  kept  there  through 
the  season  as  controls.  In  selecting  these  controls  the  animals  were 
taken  by  a  chance  selection  in  order  that  the  loco  animals  should  be 
just  as  good  as  the  controls  but  no  better.  The  controls  had  an 
uneventful  history.  All  kept  well  and  flourished  throughout  the 
summer,  and  came  out  in  the  fall  in  good  condition. 

Of  the  remaining  animals  part  were  put  in  the  loco-free  pasture  to 
be  drawn  upon  for  corral  experiments,  and  part  were  placed  in  the 
loco  pasture.  In  order  to  induce  the  loco  animals  to  eat  a  large 
amount  of  the  weed,  it  was  found  expedient  after  the  last  of  May  to 
bring  them  into  the  corrals  at  night  and  keep  them  in  until  rather  late 
the  next  morning.  By  this  treatment  they  went  to  the  pastures  in 
the  morning  very  hungry;  and  as  hungry  animals — and  this  is  espe- 
cially true  of  cattle — are  apt  to  eat  the  most  prominent  plants,  they 
would  for  an  hour  or  two  eat  loco  almost  exclusively.  After  satis- 
fying their  first  hunger  they  would  commence  to  eat  grass.  It  was 
found  that  they  ate  much  less  loco  when  kept  in  the  pasture  nights 
as  well  as  days. 

Astragalus  mollissimus  did  not  occur  in  sufficient  amount  near 
Hugo  so  that  a  pasture  could  be  arranged  where  stock  could  bo  fed, 
and  wo  found  it  necessary  for  experiments  on  this  species  to  cut  the 
loco  and  food  the  animals  in  the  corrals.  A  little  later  a  considerable 
piece  of  ground  was  found  on  the  Van  Antwerp  ranch,  about  10  miles 
south  of  Hugo,  where  the  Astragalus  niottissiiHus  was  particularly 
luxuriant.  This  piece  of  ground  was  loaned  for  experimental  pur- 
poses by  Mr.  Laurie,  and  wais  fenced  in  as  a  pasture.  Two  horses  and 
two  steers  wore  placed  in  it  on  July  13.  The  pasture  was  visited 
every  other  day  and  the  animals  were  watched  to  see  what  thoy  were 


46  THE    LOCO-WEED   DISEASE   OF   THE   PLAINS. 

eating.  It  was  necessary  to  construct  a  lane  from  the  pasture  to  a 
well  so  that  they  could  get  water,  and  in  this  lane  there  was  a  con- 
siderable amount  of  Aragallus  lamberti.  The  animals  ate  this  plant, 
but  there  is  no  evidence  that  they  ate  any  of  the  Astragalus  mollissi- 
mus.  It  was  hoped  that  as  the  grass  gradually  became  shorter  they 
would  be  forced  into  eating  the  weed,  but  to  our  surprise  within  two 
or  three  weeks  nearly  all  the  Astragalus  mollissimus  was  dead,  having 
succumbed  to  insect  enemies.  On  August  25  it  was  decided  to  take 
the  animals  out  and  abandon  the  pasture,  as  there  was  not  enough  of 
the  loco  left  to  form  any  prominent  part  of  their  food.  There  was  no 
evidence  that  the  animals  in  this  pasture  had  eaten  any  of  the  loco 
even  when  it  was  most  abundant,  so  the  pasture  experiment  upon 
Astragalus  mollissimus  must  be  considered  as  a  failure. 

All  the  animals,  when  received  in  the  spring,  with  the  exception  of 
one  horse  which  died  soon  after  its  arrival  in  Hugo,  were  in  apparently 
healthy  condition,  although  rough  and  poor,  as  they  had  just  come 
off  the  range  and  suffered  more  or  less  from  short  winter  feed.  As  the 
result  of  good  pasture,  all  commenced  immediately  to  improve.  The 
steers  in  the  loco  pasture  ate  Aragallus  lamberti  freely,  and  while  we 
at  first  imagined  that  they  were  affected  by  it,  it  soon  became  evident 
that  they  were  thriving.  T.heir  coats  became  smooth,  they  gained  in 
flesh,  and  seemed  to  give  evidence  that  the  loco  diet  was  an  excellent 
one.  The  earlier  autopsies,  too,  instead  of  showing  the  presence  of 
intestinal  parasites,  as  had  been  expected,  apparently  showed  that 
loco  animals  had  fewer  internal  parasites  than  would  be  expected  in 
normal  animals.  Our  skepticism  in  regard  to  the  poisonous  effect  of 
loco  was  confirmed,  and  it  appeared  probable  that  we  should  prove 
that  loco  was  a  myth,  or,  at  least,  a  misconception,  and  that  the  cause 
of  the  disease  must  be  sought  in  some  other  direction.  As  the  season 
progressed,  however,  occasion  was  found  for  a  change  of  opinion,  as 
will  be  seen  after  the  description  and  detailed  discussion  of  the  cases. 

The  experiment  was  carried  on  through  the  season  with  no  unex- 
pected difficulties  of  a  serious  nature,  with  the  exception  of  the  appear- 
ance of  glanders  in  the  loco  pasture.  Suddenly  one  of  the  best  of  the 
horses  developed  this  disease  in  an  acute  form  and  died  after  a  short 
illness.  This  case  was  followed  by  another,  which  also  died.  For- 
tunately the  disposition  of  the  animals  just  at  that  time  was  such 
that  there  was  reason  to  think  that  only  one  other  horse  had  been 
exposed.  This  horse  was  isolated  for  a  time,  care  was  taken  to  give 
the  pasture  a  chance  for  disinfection,  and  the  experiment  was  resumed 
with  no  further  untoward  result.  It  is  to  be  presumed  that  this  case 
resulted  from  infection  received  before  the  animals  arrived  in  Hugo. 

A  brief  history  is  given  in  the  succeeding  pages  of  some  of  the  more 
interesting  cases.  In  these  statements  the  results  of  the  autopsies 
are  not  mentioned,  as  they  are  discussed  in  some  detail  later  (see 
p.  95). 


EXPERIMENTS    WITH   CATTLE,   1905.  47 

EXPERIMENTS    WITH    CATTLE. 

Case  7. — This  steer  was  pastured  on  Aragallus  lamberti  during  the 
first  part  of  the  season.  Later  it  was  taken  into  the  corral  and  fed 
exclusively  on  cut  Aragallus  lamberti.  This  was  eaten  very  freely  for 
a  short  time,  when  the  animal  showed  distaste  for  it,  and  the  experi- 
ment was  tried  of  feeding  Astragalus  mollissimus  in  the  corral.  This 
the  steer  utterly  refused  to  eat  even  when  starved  to  it.  When  on 
occasional  days  the  animal  was  turned  out  into  the  pasture  it  would 
eat  grass  and  Aragallus  lamberti.  In  order  that  it  might  not  starve 
to  death,  it  was  afterwards  turned  into  the  Aragallus  lamberti  pas- 
ture, remaining  in  the  pasture  until  October.  In  the  middle  of  Octo- 
ber it  suddenly  began  to  show  weakness  when  walking,  this  being  espe- 
cially noticeable  in  its  hind  legs,  and  within  two  weeks  of  the  time 
when  the  first  symptoms  were  noticed  it  was  found  down  in  the  pas- 
ture, and  was  killed  and  autopsied.  This  was  a  clear  case  of  poison- 
ing from  the  eating  of  Aragallus  lamberti. 

Case  8. — This  steer  was  pastured  on  Aragallus  lamberti  from  the 
first  of  the  season  of  1905,  and  no  effects  were  noticed  until  the  latter 
part  of  July,  when  it  developed  a  solitary  habit,  and  early  in  August 
was  found  to  be  very  weak,  stepping  high  and  straddling  with 
what  are  considered  the  peculiar  loco  motions.  Plate  III,  fig- 
ures 4  and  5,  show  this  peculiarity  of  walking  quite  clearly.  On 
August  27  the  animal  was  down  and  unable  to  stand.  When  assisted 
to  get  upon  its  feet  it  would  balance  itself  and  fall  over.  Figure  6 
of  Plate  III  shows  the  animal  in  the  act  of  attempting  to  stand 
after  being  assisted.  At  this  time  it  would  eat  nothing,  but  would 
still  drink  a  little  water.  This  weakness  came  on  very  suddenly,  for 
on  August  26  it  was  driven  to  the  pasture  and  came  in  in  fairly  good 
condition.  The  steer  was  killed  on  October  28  and  the  autopsy 
made. 

Case  9. — This  steer  was  fed  on  Aragallus  lamberti  from  the  begin- 
ning of  the  season.  A  note  was  made  the  latter  part  of  May  showing 
that  the  animal  was  in  especially  good  condition  at  that  time.  At 
the  end  of  June  it  was  taken  into  the  corral  and  fed  cut  Astragalus 
mottissimus.  It  ate  freely  at  first  but  afterwards  refused  the  plant, 
and  an  attempt  was  made  to  tempt  it  by  mixing  grain  with  the  loco. 
It  ate  this  for  a  little  time,  but  soon  would  not  eat  the  loco  even  with 
the  chop,  and  because  of  the  fear  of  starvation  it  was  turned  into  the 
Aragallus  lamberti  pasture  on  July  21.  At  first  the  steer  appeared 
to  pick  up  and  presented  a  very  much  bettor  appearance.  On  August 
30  it  was  taken  into  the  corral  again  and  fed  with  a  mixture  of 
Astragalus  mottissiiMU  and  hay.  It  would  oat  the  hay,  but  did  not 
care  for  the  loco.  It  was  kept  in  the  corral  until  September  1 7,  during 
all  this  time  eating  the  hay,  but  refusing  the  loco.  As  it  was  found 
impossible  to  make  the  animal  oat  the  loco,  the  exjx'riincnt  of  feeding 


48  THE    LOCO-WEED   DISEASE   OF   THE   PLAINS. 

in  the  corral  was  abandoned,  and  it  was  turned  into  the  loco  pasture, 
where  it  commenced  to  eat  Aragallus  lamberti  again.  On  October  14 
it  was  noticed  that  the  steer  was  very  weak  and  would  fall  when 
driven  rapidly.  On  October  27  it  seemed  best  to  kill  the  animal  and 
make  an  autopsy. 

Case  10. — This  case  was  one  of  particular  interest,  as  shown  in  the 
history  of  this  and  the  succeeding  years.  The  steer  was  put  in  the 
Aragallus  lamberti  pasture  at  the  beginning  of  the  season  and  on 
July  15  was  taken  to  the  Van  Antwerp  pasture  with  the  hope  of 
getting  him  to  eat  Astragalus  mollissimus.  This  pasture  at  that  time 
was  filled  with  purple  loco,  and  there  was  a  considerable  amount  of 
Aragallus  lamberti  in  the  lane  leading  from  the  pasture  to  the  corrals. 
There  is  no  evidence  that  the  steer  ate  any  of  the  Astragalus  mol- 
lissimus, but  Aragallus  lamberti  was  eaten  by  some  of  the  animals  and 
doubtless  it  had  its  share.  Because  of  the  destruction  of  the  As- 
tragalus mollissimus,  on  August  25  it  was  returned  to  the  Aragallus 
lamberti  pasture.  The  animal  ate  more  or  less  of  the  Aragallus 
lamberti  during  the  season,  generally  less,  and  as  the  season  went  on 
it  ate  less  than  in  the  earlier  part  of  the  year.  On  September  19  it 
was  taken  into  the  corrals  and  fed  upon  Astragalus  mollissimus  and 
hay.  This  diet  was  fed  until  October  8,  but  the  steer  continuously 
refused  the  Astragalus  mollissimus.  It  was  found  impossible  to 
force  the  loco  diet  and  the  animal  was  turned  back  into  the  Ara- 
gallus lamberti  pasture  on  September  24.  During  the  rest  of  the  sea- 
son it  ate  very  little  of  the  loco  and  at  the  end  of  the  season  was  in 
good  condition.  This  animal,  it  will  be  noticed,  apparently  ate 
the  loco  mainly  because  it  was  green  and  fresh  and  did  not  at  any 
time  acquire  an  appetite  that  would  lead  it  to  eat  the  plant  in 
preference  to  grass. 

Case  11. — This  steer  was  placed  in  the  Aragallus  lamberti  pasture 
at  the  opening  of  the  season  and  ate  loco  from  the  start.  No  notice- 
able effect  appeared  until  October.  On  the  16th  of  this  month  it 
fell  when  it  was  being  driven  into  the  pasture,  and  fell  again  at  night 
as  it  was  being  brought  in,  showing  that  it  had  become  extremely 
weak.  At  this  time  it  was  poor  but  by  no  means  in  a  starving 
condition.  It  grew  steadily  worse,  and  on  October  26  was  found 
down  and  unable  to  rise.  Its  eyes  were  staring,  its  head  shaking, 
and  its  coat  rough.  It  was  killed  and  an  autopsy  made  October  27. 

Case  12. — This  was  a  black  steer  which  was  placed  in  the  Aragallus 
lamberti  pasture  at  the  beginning  of  the  season.  This  and  No.  8  ate 
loco  more  freely  than  the  other  steers,  and  it  was  noticed  that  they 
were  physicked  more  than  was  the  case  with  the  other  animals. 
During  the  first  part  of  the  season  both  appeared  to  thrive  upon  the 
Aragallus  lamberti.  On  May  30  this  animal  was  taken  into  the  corral 
and  fed  Astragalus  mollissimus  exclusively.  At  first  it  ate  freely, 


EXPERIMENTS   WITH    HORSES,   1905.  49 

but  later  ate  very  little  and  finally  refused  absolutely  to  touch  it  and 
became  very  poor.  On  June  7  Aragallus  lamberti  was  placed  before 
the  steer  and  it  immediately  commenced  to  eat  it.  Then  the  experi- 
ment was  tried  of  mixing  Astragalus  mollissimus  and  AragaUus 
lamberti,  and  it  was  found  that  the  animal  would  pick  out  the 
AragaUus  lamberti  and  eat  it  but  would  leave  all  the  Astragalus 
mollissimus.  As  it  was  evident  that  the  animal  would  not  acquire 
a  taste  for  Astragalus  moUissimus  it  was  put  on  a  diet  of  AragaUus 
lamberti  in  the  corral.  It  was  fed  this  exclusively  from  July  3  until 
July  24,  but  during  this  period  was  driven  into  the  pasture  on  Sundays. 
In  the  pasture  also  it  was  noticed  that  it  ate  Aragallus  lamberti  very 
freely.  The  AragaUus  lamberti  was  supplied  to  it  in  the  corral  in 
abundance  and  it  ate  very  readily,  but  became  steadily  poorer,  its 
coat  becoming  rough.  During  the  last  week  of  the  corral  treatment 
chop  was  mixed  with  the  loco  in  order  that  it  might  not  be  without 
nutritive  food,  but  on  July  24  it  was  so  much  reduced  that  there 
seemed  to  be  danger  of  starvation.  Accordingly  it  was  turned  out 
into  the  pasture  in  the  hope  that  it  might  pick  up.  Instead  of  picking 
up,  however,  it  grew  worse  and  became  so  weak  that  on  August  1 
it  was  found  unwise  to  try  to  get  it  into  the  corrals.  It  steadily 
grew  poorer  and  an  autopsy  was  made  on  August  5. 

EXPERIMENTS    WITH    HORSES. 

Case  17. — This  animal  was  an  iron-gray  horse,  one  of  the  best 
appearing  animals  of  the  lot  received  in  1905.  Full  of  life  and  with  a 
good  gait,  it  was  remarked  by  horsemen  who  examined  the  animals 
that  he  was  an  exceptionally  good-looking  animal.  He  was  placed 
in  the  Aragallus  lamberti  pasture  at  the  beginning  of  the  season  and 
presumably  ate  no  loco  at  that  time.  On  May  20  the  horse  was  taken 
into  the  corral  and  fed  upon  cut  AragaUus  lamberti.  He  did  not  eat 
it  readily  at  first,  but  afterwards  ate  it  fairly  well.  On  May  28  the 
horse  was  showing  a  very  decided  loss  of  flesh  and  his  excess  of  life 
had  disappeared.  He  had  become  a  sleepy  and  dull  horse.  While 
he  was  being  fed  in  the  corral  on  June  6  he  managed  to  get  hold  of  a 
box  of  Astragalus  mollifssimus  roots  and  devoured  them  very  greedily. 
It  was  noticed,  too,  that  when  a  wagon  loaded  with  Astragalus 
mollissimus  was  driven  into  the  corral  he  tried  to  get  the  loco  from 
the  sacks,  although  there  was  at  the  same  time  uneaten  Aragallus 
lamberti  in  the  corral.  It  was  found  at  this  time  that  he  would  make 
his  way  past  numerous  obstacles  to  get  at  bags  of  roots  of  As- 
tragalus moUissimus.  Although  the  way  was  barred,  he  would  find 
the  sacks  and  steal  them.  Our  first  impression  was  that  he  had  a 
real  passion  for  this  loco.  On  June  8  the  experiment  was  tried  of 
mixing  Astragalus  moU/brimus  and  Aragallus  lamberti,  when  it  was. 
79154- Bull.  112—09 4 


50  THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 

found  that  he  very  carefully  picked  out  the  mollissimus  and  left  the 
lamberti.  He  was  then  taken  out  to  the  pasture  where  both  weeds 
were  growing  to  see  whether  he  would  manifest  the  same  choice,  but 
there  he  devoted  himself  to  grass,  ignoring  both  kinds  of  loco. 
Later  on,  in  thinking  over  the  matter,  the  conclusion  was  reached  that 
while  he  might  have  had  some  desire  for  the  Astragalus  mollissimus, 
the  stealing  of  the  roots  and  the  cut  loco  might  be  explained  simply 
as  a  desire  to  steal  rather  then  a  preference  for  the  loco  itself,  because 
it  would  seem  that  if  he  really  was  anxious  to  get  the  loco  he  would 
have  picked  it  out  in  the  field,  where  there  was  an  abundance  of  it. 

The  horse  had  become  very  poor  at  this  time — July  18 — and  as 
it  was  deemed  unwise  to  leave  him  in  the  corral  he  was  put  in  the 
pasture  and  soon  showed  marked  improvement.  Up  to  this  time 
there  was  no  reason  to  think  that  he  had  eaten  Aragallus  lamberti 
in  the  field,  but  from  now  on  he  ate  it  quite  freely.  From  August 
2  to  August  25  he  was  kept  in  the  hospital  pasture  for  fear  of  infec- 
tion from  glanders.  Then  he  was  returned  to  the  Aragallus  lamberti 
pasture  and  soon  developed  a  solitary  habit,  grew  exceedingly  poor, 
and  on  September  20  was  found  in  a  dying  condition. 

Case  18. — This  animal  was  kept  in  the  Aragallus  lamberti  pasture 
from  the  beginning  of  the  season  until  May  6,  when  it  was  taken  into 
the  corral  and  fed  upon  cut  Aragallus  lamberti.  She  ate  it  very  freely 
almost  from  the  start.  From  May  9  to  May  21  she  was  kept  in  the 
pasture,  and  during  this  time  apparently  ate  very  little  Aragallus 
lamberti.  On  the  latter  date  she  was  again  taken  to  the  corral  and  fed 
with  the  cut  weed.  A  week  later,  as  she  showed  distinct  evidence  of 
having  become  poorer,  and  had  a  very  sleepy  appearance,  she  was 
put  in  the  loco  field  for  two  or  three  days,  where  she  ate  Aragallus 
lamberti  very  freely.  Then  she  was  again  taken  into  the  corral  and 
fed  exclusively  on  Aragallus  lamberti,  except  as  she  was  allowed  the 
run  of  the  pasture  on  Sundays.  She  showed  continuous  loss  of  flesh 
until  July  1,  when  she  died  very  suddenly.  During  this  time  she  had 
shown  no  peculiar  nervous  symptoms,  but  had  simply  gradually 
wasted  away.  The  result  of  the  experiment  seemed  to  indicate  that 
there  was  a  lack  of  nutritive  material  in  the  plant,  and  that  death  was 
not  only  the  result  of  poisoning,  but  probably  the  result  of  starvation. 
Plate  IV,  figures  1  and  2,  show  the  condition  of  the  animal  after  it 
had  become  locoed. 

Case  19.— ^ This  mare  was  kept  in  the  loco-free  pasture  until  August 
18.  At  that  time  she  was  taken  into  the  corral  and  fed  on  Astragalus 
mollissimus  and  hay.  She  ate  very  freely  in  the  corral,  ordinarily 
picking  out  the  loco  from  the  hay,  but  also  eating  fairly  well  of  hay. 
Later  in  the  experiment  there  was  a  period  when  she  picked  out  the 
hay  rather  than  the  loco,  but  most  of  the  time  she  seemed  to  prefer 


But.  112,  BUREAU  OF  ANIMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE 


CaseS,  July  19, 1905.    Just  before  the  locoed  con- 
dition was  particularly  evident. 


CaseS,  Augusts,  1905.  When  the  animal  showed 
typical  symptoms  of  loco  poisoning,  especially 
in  its  attitude. 


CaseS,  August  23,  1905.  Emaciated  condition  of 
animal  and  typical  loco  attitude  of  lowered  head 
and  braced  legs. 


Case  8,  August  23,  1905.     Loco  leaping  unneces- 
sarily high  in  going  over  a  rut  in  the  road. 


CaseS,  August  23,  1905.     Loco  lifting  foot  unnec- 
essarily high  in  passing  over  a  wire. 


Case  ti,  August  27,  l'A>5.      Animal  too  weak  to  stand 
unaided. 


BUL.  112,  BUREAU  OF  ANIMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  IV. 


Case  18,  May  12, 1905.     A  mare  weakened  by  k 
poisoning. 


Case  18,  June  27,  1905.     Advanced  condition  of 
loco  poisoning. 


Case  19,  May  16,  1905.     Horse  before  eating  any 
of  the  loco  weed. 


Case  19,  August  31,  1905.  Animal  eating  loco  at 
a  time  when  it  had  lost  some  flesh,  but  was  nut 
in  bad  condition. 


Case  IV,  Ot"bor  15, 1905.     Animal  in  a  very  much 
reduced  and  emaciated  condition. 


Case  19,  October  26, 1905.     Animal  just  before  its 
death. 


BUL.  112,  BUREAU  OF  AMMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  V. 


Case  524.     Peculiar  way  in  which  a  locoed  horse 
uses  its  mouth  in  attempting  to  eat. 


Case  533.     How  a  locoed  horse  will  rear  when 
suddenly  startled. 


Case  525.      Peculiar  gait  which  a  locoed   horse 
exhibits. 


Case  525.     Locoed  horse  rearing  when  suddenly 
startled  by  a  hat  thrown  out  in  front  of  it. 


Case  52V.     A  loroed  An^-nr.*    goat   unable  to 
upon  its  fei-t.  but  otherwise  fairly  well. 


Another  attitude  of  Case  52V. 


EXPERIMENTS   WITH   HORSES,   1905.  51 

the  loco.  The  experiment  was  continued  until  October  15,  with  the 
exception  of  Sundays,  when  she  was  allowed  to  run  in  the  pasture. 
During  this  time  she  lost  flesh  very  decidedly.  From  October  15  to 
October  18  she  was  kept  in  the  Aragattus  lamberti  pasture  to  see  if  the 
freedom  of  the  pasture  would  not  cause  her  to  pick  up  somewhat  in 
strength  and  in  flesh.  She  was  brought  into  the  corral  on  the  morn- 
ing of  October  18  very  poor  and  lifeless,  dragging  her  hind  feet  as 
she  walked,  the  near  foot  being  more  affected  apparently  than  the 
off  foot.  It  was  decided  to  give  her  hay  with  chop  for  a  few  days  to 
see  if  she  could  not  be  brought  out  of  the  diseased  condition.  She 
refused  to  eat  the  chop  and  on  October  21  would  eat  neither  chop. nor 
oats,  but  would  eat  hay.  She  remained  in  the  corrals  until  October 
26,  when  she  died  and  the  autopsy  was  made.  The  death  in  this  case 
was  at  least  partly  caused  by  starvation  as  well  as  by  the  effect  of  the 
poison.  Plate  IV,  figures  3  to  6,  show  the  change  in  the  condition  of 
the  animal. 

Case  20. — This  was  a  yearling  mare  which  was  placed  in  the  Ara- 
gaUus lamberti  pasture  on  May  8.  She  was  not  observed  to  be  eating 
any  loco  until  the  latter  part  of  August.  After  that  time  she  ate  more 
or  less  Aragallus  lamberti.  We  do  not  know  that  the  mare  ate  any 
large  amount  at  any  time,  but  she  grew  poorer  steadily  and  disap- 
peared on  September  21,  and  was  found  dead  a  day  or  two  later. 
The  animal  was  interesting  in  that  the  poison  took  effect  in  a  compara- 
tively short  time  and  rather  unexpectedly. 

Case  24. — No.  24  was  a  6-year-old  horse,  a  good-looking  animal. 
He  moved  with  erect  head  and  long  step,  and  was  marked  as  one  of 
the  better  appearing  horses  in  the  experiment.  He  remained  in  the 
loco-free  pasture  until  the  end  of  May  and  then  was  fed  in  the  corral 
upon  cut  Astragalus  mollissimus.  He  ate  it  very  freely,  in  fact  would 
eat  about  all  that  was  furnished.  This  diet  was  continued  until 
June  11,  when  the  horse  was  turned  out  for  a  day.  When  returned  to 
the  corral  he  took  the  loco  again  very  readily,  although  he  did  not 
seem  hungry.  There  was  no  evidence  that  the  horse  ate  any  loco  at 
all  while  in  the  field.  At  first  there  seemed  to  bo  no  effect  from  this 
feeding  experiment.  The  animal  did  not  lose  flesh,  retained  its 
spirits,  and  showed  no  symptoms  of  unhealthy  nervousness.  After 
the  middle  of  June,  however,  he  gradually  lost  flesh  and  early  in  July 
he  was  so  poor  that  it  seemed  likely  that  wo  might  have  a  case  of 
starvation,  so  he  was  turned  into  the  pasture  to  pick  up.  The  animal 
still  seemed  to  have  fairly  good  spirits,  carrying  its  head  high,  but  the 
coat  was  rough  and  the  bones  exceedingly  prominent.  In  the  pasture 
he  ate  the  grass,  not  caring  for  the  loco,  and  it  was  ho|>ed  he  would 
gradually  pick  up  and  got  in  form  for  further  experimentation.  Some- 
what to  our  surprise  on  July  8  the  horse  was  found  dead.  He  lay 


52  THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 

under  a  barbed  wire  fence  and  it  was  evident  had  kicked  about  for  a 
considerable  time  before  death.  His  death  could  not  have  been 
entirely  the  result  of  weakness. 

It  may  be  mentioned  as  a  feature  of  this  case  that  during  the  latter 
part  of  the  horse's  stay  in  the  corral  tumors  as  large  as  a  small  fist, 
one  or  two  at  a  time,  would  appear  upon  the  groin.  These  appeared 
and  disappeared  in  a  day  or  two.  None  were  noticeable  at  the  time 
of  death. 

Case  26. — This  horse  was  taken  from  the  loco-free  pasture  on  July 
13  to  the  Van  Antwerp  pasture  to  experiment  with  Astragalus  mol- 
lissimus.  There  is  no  evidence  that  the  animal  ate  any  of  the 
Astragalus  mollissimus  in  this  pasture,  nor  does  it  seem  probable  that 
it  ate  the  AragaUus  lamberti. 

Because  of  the  death  of  the  purple  loco  the  horse  was  brought  back 
and  placed  in  the  AragaUus  lamberti  pasture  on  August  25.  It  began 
to  eat  the  loco  within  two  weeks,  and  soon  it  and  its  companion  horse 
developed  the  solitary  habit.  The  horse  ate  the  weed  continuously 
until  September  15,  when  it  died  somewhat  suddenly.  The  animal 
before  this  had  shown  a  peculiar  straddling  gait  which  was  especially 
noticeable  in  its  hind  legs,  but  it  did  not  seem  to  be  particularly  weak 
nor  in  a  bad  condition. 

CASES    OF    CATTLE    AND    HORSES    NOT    SUBJECTS    OF    EXPERIMENT. 

Besides  work  upon  the  station  animals  a  considerable  number  of 
locoed  cattle  and  horses  were  examined  at  ranches  near  Hugo  and 
at  other  points  in  Colorado.  In  most  cases  autopsies  were  made. 
Some  of  the  more  interesting  cases  will  be  briefly  mentioned  below. 

Case  501 . — This  was  a  cow  belonging  to  Mr.  Frank  Ewing,  of  Hugo. 
When  found  the  animal  was  too  badly  decayed  for  autopsy,  but  it 
was  a  particularly  interesting  case  of  the  very  pronounced  swelling 
under  the  jaw,  which  is  considered  as  one  of  the  peculiar  symptoms 
of  loco  poisoning.  The  tumor  was  filled  with  a  clear  serous  fluid. 

Case  503. — This  was  a  2-year-old  steer  belonging  to  Mr.  William 
Hazel,  of  Hugo.  This  case  is  interesting  as  being  a  typical  locoed 
range  steer.  The  animal  was  found  near  a  watering  place  about  2 
miles  from  the  loco  station.  It  was  down,  but  with  head  erect.  Its 
eyes  were  sunken  and  staring,  its  coat  rough  and  very  poor.  When 
startled  it  responded  with  peculiar  nervous  twitchings. 

Case  519. — This  was  the  first  horse  upon  which  an  autopsy  was 
made.  It  belonged  to  Mr.  Charles  Johnson,  of  Akron,  Colo.,  and  had 
been  considered  one  of  his  best  horses.  The  animal  had  been  eating 
loco  for  two  or  three  years.  It  was  poor  in  flesh,  with  shaggy  mane 
and  tail,  its  coat  was  rough,  the  hair  being  off  in  patches,  and  it 
walked  with  a  peculiar  stiff,  irregular  motion  of  the  legs,  and  had 
become  absolutely  worthless. 


MISCELLANEOUS  CASES,  1905.  53 

Case  524- — This  was  a  colt  belonging  to  Mr.  Kendrick,  of  Seibert, 
Colo.  The  interest  connected  with  this  animal  was  largely  in  its 
peculiar  way  of  eating.  It  had  been  taken  into  the  corral  to  feed  in 
order  to  get  rid  of  the  loco  symptoms.  It  was  in  good  flesh,  but 
very  nervous,  constantly  walking  about  the  corral.  Plate  V,  figure 
1,  shows  the  peculiar  nibbling  way  of  eating,  a  motion  that  is  char- 
acteristic of  locoed  animals. 

Case  525. — This  was  a  horse  belonging  to  Mr.  John  Lieber,  of 
Hugo,  and  is  referred  to  in  this  place  because  of  the  particularly 
good  pictures  (PI.  V,  figs.  3  and  4)  which  were  obtained  of  its  atti- 
tudes, which  show  the  peculiar  gait  of  a  locoed  animal  and  the 
attitude  which  one  is  likely  to  assume  when  startled.  The  horse  was 
very  poor,  being  little  but  skin  and  bones,  with  rough  coat  and  shaggy 
mane  and  tail.  When  walking  over  a  railroad  track  it  was  noticed 
that  its  feet  were  lifted  very  high  in  order  to  clear  the  rails. 

Case  533. — In  this  case,  too,  a  particularly  good  picture  (PI.  V, 
fig.  2)  was  obtained  of  the  position  assumed  when  startled.  This 
horse  was  seen  on  a  ranch  north  of  Claremont,  Colo. 

( 'ax?  529. — This  case  was  one  of  considerable  interest,  as  being  the 
only  case  of  a  locoed  goat  encountered  during  the  season's  work. 
The  animal  was  an  Angora  goat  belonging  to  Mr.  Lon  Foote,  of  Hugo. 
It  was  received  at  the  experiment  station  on  September  23,  1905, 
and  at  that  time  was  unable  to  stand.  The  animal  moved  its  legs 
spasmodically,  and  by  great  effort,  with  assistance,  would  get  upon 
its  feet,  but  would  soon  fall  down,  falling  clear  over,  with  its  head 
prone  upon  the  ground.  It  would  eat  grain  very  freely  and  would 
drink  readily.  The  first  impression  on  seeing  it  as  it  lay  upon  the 
ground  was  that  it  was  in  the  agonies  of  death,  because  of  the  peculiar 
convulsive  movements  of  its  legs.  The  owner  said  that  it  had  been 
in  the  corral  since  spring.  During  the  winter  it  had  eaten  very 
freely  of  Aragallns  lamberti,  and  its  present  condition  was  considered 
as  entirely  due  to  this  food.  The  goat  was  kept  at  the  loco  station 
from  September  23  to  September  29,  and  during  that  time  showed 
very  little  change  in  condition,  except  that  it  grew  somewhat  weaker. 
Within  two  or  three  days  after  arrival  at  the  ranch  the  goat  was 
unable  to  stand  upon  its  feet  at  all,  and  could  not  even  sit  with  the 
head  in  an  erect  position  for  any  length  of  time.  When  put  in  a 
sitting  position  so  that  it  could  eat,  the  goat  would  do  so  for  a  little 
time,  then  with  a  peculiar  jerky,  convulsive  movement  the  head 
would  be  thrown  back  bit  by  bit,  finally  falling  over  on  the  side,  with 
the  horns  lying  flat  on  the  ground.  As  it  seemed  probable  that  noth- 
ing more  could  be  gained  by  keeping  it,  the  goat  was  killed  and  au- 
topsied.  Plate  V,  figures  />  and  0,  show  the  characteristic  attitude* 
assumed  l>\  the  animal. 


54  THE    LOCO-WEED   DISEASE    OF   THE   PLAINS. 

SUMMARY    OF    FIRST    SEASON'S    WORK. 

The  detailed  discussion  of  the  results  of  the  work  of  1905  will  be 
taken  up  after  the  description  of  the  cases  of  the  second  year.  It 
may  be  well,  however,  to  insert  here  the  statement  which  was  formu- 
lated at  the  end  of  the  season  as  embodying  the  results  so  far  obtained. 

1.  There  is  no  longer  any  question  of  the  poisonous  effect  of  the 
loco  weeds.     The  results  of  the  feeding  experiment  at  the  ranch  seem 
to  prove  conclusively  that  Aragallus  lamberti,  or  rattleweed,  when 
eaten  for  a  prolonged  period  of  time,  has  an  effect  of  poisoning  upon 
the  nervous  system,  which  leads  to  a  lack  of  muscular  coordination. 
The  animal's  nervous  system  becomes  impaired  to  such  an  extent 
that  the  nutritive  functions. are  interfered  with  and  the  victim  per- 
ishes by  starvation.     The  presence  of  ulcers  in  the  fourth  stomach 
of  some  of  the  steers  may  possibly  be  a  characteristic  lesion.     The 
finding  of  a  serous   exudate  in  the  spinal  canal  in  certain  of  the 
autopsies  would  seem  to  indicate  that  this  is  another  definite  lesion 
produced  by  loco. 

2.  Aragallus  lamberti  will  evidently  poison  both  horses  and  cattle; 
presumably  also  it  has  the  same  effect  upon  sheep,  although  the 
season's  experiments  did  not  have  enough  to  do  with  sheep  to  make 
this  at  all  evident. 

3.  Astragalus  mollissimus  has  the  same  general  effect  upon  horses 
and  sheep  as  Aragallus  lamberti.     They  do  not  eat  it  as  readily,  but 
when  eaten  it  has  the  same  general  effect. 

4.  Cattle  can  be  poisoned  by  Astragalus  mollissimus,  though  as  a 
matter  of  fact  they  rarely  eat  it.     It  was  shown  quite  clearly  by  the 
feeding  experiments  that  it  was  very  difficult  to  make  cattle  eat  this 
weed.     In  the  neighborhood  of  Hugo,  Colo.,  loco  poisoning  may  be 
considered    as    almost    entirely    due    to    Aragallus    lamberti.     It   is 
noticed,  too,  that  in  parts  of  the  State  where  Astragalus  mollissimus 
is  the  common  loco  plant,  like  the  region  around  Holyoke,  locoed 
cattle  are  almost  entirely  unheard  of.     The  same  may  be  said  of  the 
Panhandle  in  Texas,  where  the  common  loco  plant  is  Astragalus 
mollissimus  and  where  locoed  cattle  are  very  unusual.     It  seems  prob- 
able, then,  that  the  generalization  may  be  made  that,  while  both 
these  plants  will  produce  poisonous  effects  upon  both  cattle  and 
horses,  it  is  very  rare  that  cattle  will  eat  Astragalus  mollissimus,  and 
that  so  far  as  the  cattle  industry  is  concerned  the   loss  from   this 
plant  is  probably  exceedingly  small. 

In  the  case  of  horses  it  appears  that  while  they  eat  Astragalus 
mollissimus  more  readily  than  do  cattle,  they  are  not  likely  to  eat 
it  unless  forced  by  shortness  of  food,  while  both  horses  and  cattle 
may  contract  the  habit  of  eating  Aragallus  lamberti  even  when  an 
abundance  of  food  is  present. 


SUMMARY   OF   FIRST   SEASON'S   WORK.  55 

5.  It  has  been  argued  by  some  that  the  so-called  loco  disease  was 
simply  the  result  of  starvation,  and  that  if  animals  had  sufficient  to 
eat  there  would  be  no  trouble  from  loco.  The  feeding  experiments 
seem  to  indicate,  however,  a  specific  poisonous  effect  of  the  weeds. 
The  animals  that  were  fed  upon  loco  alone  starved  to  death,  but  animals 
were  also  given  abundance  of  other  feed  mixed  with  loco,  and  in 
these  cases  they  also  died,  showing  conclusively  that  loco  kills  not 
simply  by  a  lack  of  nutrition,  but  because  of  a  definite  poisonous 
effect  produced  by  the  plant  itself. 

At  the  end  of  the  season,  about  the  middle  of  November,  the  sur- 
viving animals  were  taken  to  a  ranch  for  the  winter,  where  they  were 
pastured  and  fed  hay  when  necessary,  but  none  of  them  had  any 
loco.  It  was  intended  that  they  should  have  the  same  care  that 
would -ordinarily  be  given  by  the  stockmen  to  animals  that  were  kept 
under  common  range  conditions. 

WORK  OF  THE  SECOND  AND  THIRD  SEASONS. 

The  work  of  the  first  season,  as  has  been  indicated  above,  seemed 
to  bring  certain  fairly  definite  results.  The  experiment,  however, 
was  on  too  small  a  scale,  the  number  of  animals  was  too  small,  and 
the  general  character  of  the  experiment  too  circumscribed  to  permit 
one  to  speak  at  all  dogmatically  as  to  the  deductions  which  should  be 
made.  The  autopsies  in  many  cases  were  performed  too  hastily  for 
satisfactory  results.  The  labor  of  conducting  the  routine  work  was 
greater  than  had  been  expected  and  taxed  the  capacity  of  the  station 
force  seriously.  It  was  therefore  necessary  to .  repeat  the  work  of 
the  first  season  on  a  larger  scale  if  possible,  and  thus  confirm  or 
modify  the  tentative  conclusions  which  had  been  reached.  The  plan 
of  the  second  season  (1906)  then  was  on  the  same  general  lines  as 
that  of  the  first  season,  but  modified  somewhat  by  the  experience 
already  undergone.  For  example,  there  seemed  no  longer  any  doubt 
of  the  poisonous  nature  of  the  loco  weeds,  so  that  it  seemed  unneces- 
sary to  carry  any  large  number  of  control  animals.  The  season's 
work  as  planned  involved: 

1.  Pasture  feeding  on  Aragallus  lamberti  as  in  the  preceding  season. 

2.  Corral  feeding  on  both  Astragalus  inollwsimus  and  Aragallus 
lamberti  under  various  conditions. 

.3.  Careful  post-mortem  examinations  to  determine  the  definite 
lesions  characteristic  of  the  disease,  the  work  of  the  first  season  not 
being  conclusive  on  this  point. 

4.  The  determinations  of  ttie  effects  of  loco  on  sheep  as  well  as  on 
horses  and  cattle. 

5.  Experimentation  with  such  remedial  measure's  as  were  indicated 
by  the  conclusions  already  reached. 


56  THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 

6.  The  extension  of  the  knowledge  of  loco  plants  as  much  as 
possible. 

The  preceding  work  and  the  main  work  of  the  second  year  were 
writh  Astragalus  mottissimus  and  Aragallus  lamberti  in  a  restricted 
area.  Not  only  should  more  be  known  of  the  extent  of  the  damage 
from  these  two  species,  but  it  was  desirable  to  know  to  what  extent, 
if  any,  other  related  plants  are  the  cause  of  similar  results.  At  the 
conclusion  of  the  second  season  it  appeared  that  the  first  four  heads 
had  been  covered  fairly  well,  while  a  fair  beginning  had  been  made 
with  the  last  two,  although  the  work  was  incomplete. 

In  addition  to  the  work  at  Hugo,  in  which  the  Colorado  Agricul- 
tural Experiment  Station  cooperated  as  in  the  preceding  season,  the 
Department  carried  on  a  station  at  Woodland  Park,  Colo.  Woodland 
Park  is  near  Pike's  Peak,  and  the  conditions  are  very  different  from 
those  in  the  plains,  although  the  most  abundant  loco  plant  in  this 
region  is  considered  by  botanists  to  be  specifically  identical  with  the 
Aragallus  lamberti  of  the  plains.  Another  loco  plant,  Astragalus 
nitidus,  is  abundant  in  the  pastures  in  this  neighborhood. 

In  cooperation  with  the  Nebraska  experiment  station,  a  feeding 
experiment  writh  Astragalus  mollissimus  wras  also  carried  on  at 
Imperial,  in  western  Nebraska.  In  this  region  the  only  abundant 
species  of  loco  is  Astragalus  mollissimus. 

The  feeding  experiment  during  the  second  season  was  carried  on 
in  the  same  general  way  as  during  the  preceding  year.  Of  the  cattle, 
Nos.  1,  30,  31,  43,  46,  and  47,  and  of  the  horses  Nos.  49,  51,  54,  55, 
61,  and  65  were  placed  in 'the  loco-free  pasture  as  controls  and  kept 
there  throughout  the  entire  season.  All  prospered  and  were  in  good 
condition  at  the  end  of  the  season.  Of  the  others,  some  were  pastured 
in  the  Aragallus  lamberti  pasture  and  some  were  fed  Aragallus  lam- 
berti and  hay  in  the  corrals.  Twenty-three  head  of  cattle  were  sub- 
jected to  the  feeding  experiments,  and  of  these  eight  were  dead  at  the 
end  of  the  season  and  two  were  locoed,  but  recovered  under  treat- 
ment. The  history  of  some  of  the  more  interesting  cases  follows. 
In  these  cases,  as  in  those  of  1905,  the  results  of  the  autopsies  are  dis- 
cussed later  on  in  this  paper. 

EXPERIMENTS    WITH    CATTLE. 

Case  2. — This  was  a  steer  which  had  been  kept  in  the  loco-free 
pasture  during  the  entire  season  of  1905  and  during  the  season  of 
1906  until  May  9.  It  was  one  of  the  best  appearing  animals,  a  par- 
ticularly good  looking  and  high  spirited  steer.  On  the  latter  date  it 
was  placed  in  the  corral  and  fed  on  a  mixture  of  hay  and  fresh  cut 
Aragallus  lamberti.  At  first  it  refused  to  eat  the  loco  plant,  and  when 
the  latter  was  mixed  with  the  hay  would  shake  out  the  loco  weed  and 


EXPERIMENTS  WITH   CATTLE,   1906.  57 

eat  the  hay,  but  after  a  few  clays  in  the  corral  it  ate  the  loco  with  a 
fair  degree  of  readiness.  The  steer  was  kept  in  the  corral  until  August 
19,  except  for  an  occasional  day,  when  it  was  permitted  to  run  out  in 
the  Aragallus  lamberti  pasture.  On  May  27,  when  it  was  run  out  in  the 
pasture  it  was  noticed  that  it  would  eat  nothing  but  Aragallus  lam- 
berti, and  for  some  time  before  this  date  in  the  corral  it  had  eaten 
loco  rather  than  hay. 

The  first  positive  symptoms  from  the  eating  of  Aragallus  lamberti 
were  noted  on  July  19,  when  it  fell  as  it  was  passing  through  a  gate  to 
go  to  water.  From  this  time  on  it  always  showed  more  or  less  symp- 
toms of  being  gate  shy;  that  is,  would  stoop  in  passing  through  a  gate 
as  though  endeavoring  to  get  under  a  wire.  It  became  hard  to  drive 
and  was  more  and  more  stupid  as  time  went  on.  This  stupidity  was 
especially  marked  because  of  the  prior  activity  of  the  animal.  When 
kept  in  the  loco-free  pasture  it  had  been  the  source  of  a  good  deal  of 
trouble,  because  it  was  inclined  to  break  through  the  fences  and, 
when  through,  was  caught  only  with  difficult}'.  During  the  first 
week  in  August  the  animal  lost  its  appetite  and  showed  great  nervous- 
ness, its  head  shaking  as  though  it  had  the  palsy.  Sometimes  in  pass- 
ing through  a  gate  it  not  only  would  crouch  but  would  fall  down. 
Plate  VII,  figure  1,  shows  the  peculiar  attitude  which  it  assumed  at 
such  times.  It  became  very  much  constipated,  and  on  August  12, 
when  driven  out  of  the  pasture,  would  continually  stumble  and  fall. 
It  suddenly  grew  worse,  and  on  August  23  fell  and  wTas  unable  to  get 
up  again.  It  died  on  the  26th  and  wras  autopsied. 

Case  3. — This  was  another  steer  remaining  from  the  season  of  1905. 
It  was  in  the  loco  pasture  during  that  season,  but  did  not  show  any 
marked  results  of  poisoning.  In  the  season  of  1906  it  was  placed  in 
the  Aragallus  lamberti  pasture  in  the  spring  and  immediately  com- 
menced to  eat  the  weed.  It  ate  very  freely  and  began  early  to  show 
the  effect  of  the  poison.  On  July  3  it  was  noticed  standing  by  itself 
in  the  pasture,  and  on  July  9  its  condition  was  so  marked  that  it 
seemed  desirable  to  take  it  to  the  corral  and  attempt  remedial  meas- 
ures. The  steer  was  accordingly  fed  hay  and  chop,  part  of  the  hay 
being  alfalfa.  It  gradually  grew  worse,  however,  and  on  July  16 
was  found  down;  in  the  afternoon  it  was  deemed  best  to  kill  it  and 
make  an  autopsy.  Plate  VI,  figure  1 ,  shows  the  animal  just  before  its 
death,  and  Plate  VI,  figure  2,  shows  the  interior  of  the  wall  of  the 
fourth  stomach,  with  the  ulcers  which  were  present  in  considerable 
numbers. 

Case  10. — This  was  also  an  animal  which  had  been  experimented 
upon  during  the  preceding  season  and  had  shown  only  the  general 
effect  of  what  may  be  called  moderate  eating.  It  was  placed  in  the 
ArayaUu*  lamberti  pasture  in  the  beginning  of  the  spring  of  1906  and 
ate  the  weed  with  considerable  freedom.  It  was  noticed  toward  the 


58 


THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 


end  of  April  that  the  animal  was  very  thin,  its  coat  rough,  and  that 
it  walked  with  its  head  down  in  a  spiritless  way.  This  probably  was 
due  not  so  much  to  the  loco  feeding  as  to  the  short  feeding  during  the 
winter,  as  it  had  been  in  the  loco  pasture  only  a  short  time.  From 
this  time  it  commenced  to  eat  AragaUus  lamberti,  but  not  very  freely. 
It  then  weighed  507  pounds;  on  May  7  its  weight  was  590  pounds,  and 
its  maximum  weight  during  the  summer  was  reached  on  September 
7,  when  it  weighed  840  pounds. 

The  history  of  this  animal  was  interesting  because,  while  during 
the  two  seasons  it  ate  more  or  less  of  the  loco,  it  never  ate  it  in  any 
very  large  amount.  It  could  well  be  compared  to  the  moderate 
drinker  of  alcoholic  liquors,  for  it  was  not  poisoned  so  as  to  show  the 
effect  of  the  weed  in  a  very  marked  degree,  but  it  was  affected  to  the 
extent  of  not  gaining  as  much  as  would  naturally  be  expected.  The 
curve  of  the  weight  (see  fig.  4)  shows  this  effect,  for  if  this  curve  is 


1 

1906  APRti 

M 

4Y 

A/E 

JULY 

/H/GUSr 

5^/Vif 

/•/^W 

OCWSEff 

/W9AT 

1906 

750 

2C 

—  s 

-J5!5*- 

^-  — 

700 

^ 

z^ 

650 
600 

^ 

^*- 

FIG.  4. — Curve  of  weight  of  steer  No.  10,  1906. 

compared  with  those  of  animals  in  good  pasture  it  will  be  noticed 
that  it  is  flatter,  while  the  animals  in  good  pasture  gained  with  great 
rapidity  until  the  end  of  the  season.  This  was  the  only  steer  that 
refused  to  eat  AragaUus  lamberti  in  any  large  amount. 

During  the  season  of  1907  No.  10  was  herded  with  the  other  experi- 
ment animals  in  the  loco  pasture  and  continued  as  in  the  preceding 
seasons  to  eat  more  or  less  of  the  AragaUus  lamberti.  At  no  time,  how- 
ever, did  the  steer  eat  enough  to  show  marked  effects  from  the  poison. 
At  the  end  of  the  season  the  gain  in  weight  was  once  more  much  less 
than  it  should  have  been  normally  (see  fig.  5),  but  this  failure  to 
increase  in  weight  was  the  only  evident  effect  of  the  loco  poison. 
Case  10  is  a  good  example  of  the  possibilities  of  cattle  eating  loco 
season  after  season  without  showing  serious  effects  from  the  poison. 

Case  32. — This  was  an  Aberdeen  Angus  cow  carrying  a  registry 
tag.  She  was  placed  in  the  AragaUus  lamberti  pasture  in  April, 
1906,  and  commenced  immediately  to  eat  the  plant.  She  dropped 
a  calf  on  May  6.  She  continued  to  eat  AragaUus  lamberti,  and  her 


Buu.  112.  BUREAU  OF  AMMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  VI. 


FIG.  1.— CASE  3.    EFFECT  OF  LOCO   POISONING,  SHOWN  IN  EMACIATION  AND 
DEJECTED  ATTITUDE,  JUST  BEFORE  DEATH  OF  ANIMAL. 


FIG.  2.-INNEK  WALL  OF  FOURTH  STOMACH  OF  CASE  3.  SHOWING  ULCERS 
UPON  ITS  SURFACE. 


BUL.  112,  BUREAU  OF  ANIMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  VII. 


Case  2,  July  25,1906.     Steer  bending  low  to  avoid  Case  34.     Another  case  similar  to  that  in  Fig.  1. 

an  imaginary  obstruction  above  it  while  passing 
through  a  gate. 


. 


Case67,  May  1,1906.     A  bright  heifer  calf  shortly          Case  67,  July  5,  1906.      Calf  shown   in   Fig.  3. 
after  birth.  Effects  of  loco  which  it  had  eaten  in  imitation 

of  its  mother. 


Case  67,  October  16. 1906.    Calf  with  typical  symp-          Case  67,  October  19,  1906.     Animal   just  before 
toms  of   loco.     The  long  hair  of  the  face  is  death. 

especially  noticeable. 


EXPERIMENTS   WITH    CATTLE,   1906. 


59 


weight  on  July  5  was  only  850  pounds  as  compared  with  1,025  pounds 
on  May  3.  Of  course  her  weight  would  have  been  reduced,  in  any 
caser,  at  the  time  of  the  birth  of  the  calf,  but,  under  normal  condi- 
tions, being  a  large,  strong  animal,  the  weight  should  have  been 
regained  in  a  short  time. 

The  effect  of  loco  upon  her  coat  was  noticed  on  July  19,  although 
the  symptoms  were  not  at  that  time  very  pronounced.     They  became 


1 

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Fio.  5.— Curve  of  weight  of  steer  No.  10, 1907. 

more  and  more  so,  however,  and  on  July  30  she  had  great  difficulty 
in  getting  up  after  being  down,  and  walked  in  the  typical  loco 
fashion.  She  died  on  August  26.  The  case  was  one  of  especial 
interest  because  she  commenced  to  eat  the  loco  almost  immediately 
when  out  in  the  pasture,  and  the  effects  came  in  a  comparatively 
short  time.  The  effect  of  the  poisoning  on  her  weight  is  shown  in 
figure  6. 


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KlO.  8.— Curve  of  weight  of  cow  No.  'Si. 

Case  34- — This  was  a  cow  which  commenced  to  oat  loco  immediately 
after  being  placed  in  the  AragdHus  bunbtrti  pasture  in  the  spring. 
She  gave  birth  to  a  calf  on  May  3.  The  calf  was  weak  and  unable  to 
stain  I  and  lived  only  a  few  days.  There  was  really  no  reason,  how- 
ever, for  supposing  that  the  weak  condition  of  the  calf  was  due  to 
Arayattus  lamberti.  She  ate  AragaUus  lamberti  with  great  freedom, 
and  earlv  in  June  it  was  noticed  that  at  times  she  would  go  from 


60 


THE   LOCO-WEED   DISEASE   OF  THE   PLAINS. 


one  plant  to  another,  eating  nothing  at  all  except  the  loco  weed. 
Symptoms  of  loco  poison  were  shown  in  a  marked  degree  a  little 
before  the  middle  of  July.  Plate  VII,  figure  2,  shows  the  condition 
of  the  animal  at  this  time,  the  picture  being  taken  on  July  9.  It 
also  shows  the  peculiar  crouching  attitude  which  the  animal  assumed 
in  going  through  a  gate — bending  down  as  though  she  were  attempt- 
ing to  get  under  a  wire.  On  July  19  she  was  very  poor,  had  a  rough 
coat,  straddled  as  she  walked,  and  showed  marked  lack  of  muscu- 
lar coordination;  she  was  also  very  weak.  She  was  kept  on  Ara- 
gallus  lamberti  until  August  8.  The  cow  was  nervous,  had  lost  con- 
trol of  her  muscles  to  a  very  marked  degree,  and  showed  great 
difficulty  in  crossing  over  even  the  slightest  obstructions.  On  Aug- 
ust 8  she  was  kept  in  and  fed  alfalfa  and  hay,  and  attempts  were 


FIG.  7. — Curve  of  weight  of  cow  No.  37. 

made  to  give  her  certain  medicinal  remedies.  She  grew  worse  until 
August  16,  when  she  died  and  was  autopsied. 

Case  37. — This  was  a  Hereford  cow  with  a  registry  tag.  She  was 
placed  in  the  Aragallus  lainberti  pasture  in  the  spring  and  imme- 
diately commenced  to  eat  the  loco  weed.  At  this  time  she  weighed 
830  pounds.  She  gave  birth  to  a  calf  April  28.  She  began  to  show  the 
effect  of  the  loco  poison  about  the  middle  of  July,  and  the  symptoms 
increased  gradually  until  August  31,  when  she  would  fall  down  when 
walking.  On  September  10  she  was  kept  in  the  corral,  as  she  was  at 
this  time  very  weak,  and  was  fed  hay.  She  weighed  then  690 
pounds.  On  September  11  she  was  down  and  remained  down  until 
September  14.  During  this  time  she  would  eat  very  little.  On 
September  14  she  was  barely  alive,  and  was  killed  in  the  afternoon 
and  autopsied.  The  curve,  figure  7,  shows  the  decline  in  weight 
resulting  from  loco  poisoning. 

Case  45- — This  was  a  cow  which  was  placed  in  the  loco-free  pas- 
ture in  the  spring  of  1906,  weighing  at  this  time  775  pounds.  The 
latter  part  of  May  she  was  taken  into  the  corral  to  feed  fresh  cut 
Aragallus  lamberti  in  order  to  determine  whether  loco  weed  might 
not  produce  abortion.  She  was  apparently  about  three  months 


EXPERIMENTS   WITH   CATTLE,   1906. 


61 


along  with  calf.  For  the  first  two  or  three  days  the  hay  was  omitted 
from  her  feed  in  order  to  get  her  to  eat  the  AragaUus  lamberti  more 
freely.  After  that  time,  however,  she  was  furnished  with  an  abun- 
dance of  hay  so  that  there  might  be  no  question  of  starvation.-  She 
ate  the  weed  from  the  start,  although  not  very  freely  at  first,  but 
soon  acquired  the  habit,  and  when  turned  out  into  the  pasture  it 
was  noticed  that  she  would  go  from  one  AragaUus  lamberti  plant  to 
another,  seeming  to  hunt  for  the  loco,  desiring  it  very  much  more 
than  grass.  On  July  21  she  was  somewhat  gate  shy,  and  a  few 
days  later  her  motions  in  going  through  a  gate  very  closely  resembled 
those  of  steer  2.  Her  calf  was  dropped  on  August  5,  and  it  was  evi- 
dent that  it  was  a  premature  birth.  The  calf  weighed  only  14 
pounds,  was  about  24  inches  long,  the  hair  was  not  formed,  and  it 
may  be  assumed  that  it  was  not  more  than  six  months  along. 

It  would  seem  probable  in  this  case  that  AragaUus  lamberti  had 
induced  the  premature  birth.  She  continued  to  eat  the  AragaUus 
lamberti  and  gradually  grew  weaker  little  by  little,  losing  her  appetite 
and  not  caring  to  eat  much  of  anything.  On  August  18  she  was 


1 

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Fio.  8.— Curve  of  weight  of  calf  No.  00. 

down  and  could  not  get  up.  She  was  fed  and  furnished  water,  but 
did  not  get  up  again,  and  died  on  August  31. 

Case  66. — This  was  a  male  calf  dropped  by  cow  32  on  May  6. 
Its  weight  on  July  5  was  138  pounds.  By  the  middle  of  July  it  was 
eating  a  good  deal  of  AragaUus  lamberti,  and  continued  to  eat  it 
very  freely;  the  effects  of  the  poison  were  evident  by  the  1st  of 
August.  At  that  time  the  calf  was  decidedly  constipated  and 
began  to  be  somewhat  dull.  On  August  9  it  was  very  weak  and 
would  not  follow  the  others  going  to  the  pasture,  but  laid  down  and 
remained  away  from  the  rest  of  the  herd.  On  Scpteml>or  7  its 
weight  was  190  pounds.  On  October  9  the  weight  had  become 
reduced  to  170  pounds.  On  October  17  the  animal  was  taken  into 
the  corral  for  dosing.  It  was  pretty  far  gone,  however,  anil  in  a 
blixzard  on  October  21  the  exposure  caused  its  death. 

This  case  was  particularly  interesting,  as  the  calf  was  born  of  a 
cow  that  was  eating  loco,  and  presumably  learned  to  eat  from  its 
mother.  Although  a  bright,  healthy,  and  strong  calf  at  the  outset 
it  made  very  little  gain  in  weight  and  gradually  succumbed.  The 
curve,  figure  8,  shows  the  changes  in  weight. 


62 


THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 


Case  67. — This  was  a  Hereford  calf  dropped  by  cow  37  on  April  28. 
It  was  kept  with  its  mother  in  the  Aragallus  lamberti  pasture,  and  by 
the  middle  of  June  was  eating  pretty  freely  of  the  weed.  On  July  5 
its  weight  was  160  pounds.  Marked  effects  from  the  loco  eating 
appeared  about  the  1st  of  August,  when  it  became  constipated  and 
dull,  and  in  other  ways  showed  symptoms  of  the  poison.  The  weight, 
however,  increased  until  September  7,  when  it  weighed  210  pounds. 
On  September  19  it  was  put  in  good  pasture,  with  the  intention  of 


1 

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FIG.  9.— Curve  of  weight  of  calf  No.  67. 

making  some  attempt  to  cure  its  locoed  condition.  From  this  time 
on  it  was  kept  away  from  the  loco  and  was  dosed.  It  continually, 
lost  weight,  however,  and  on  October  9  weighed  only  182^  pounds. 
Its  decline  was  gradual,  and  it  showed  all  the  symptoms  of  typical 
loco.  It  became  very  poor,  with  rough  coat,  dull  eyes,  and  in  walk- 
ing its  head  was  down  in  an  attitude  of  peculiar  dejection.  Plate 
VII,  figure  3,  shows  the  animal  soon  after  birth,  when  it  was  a  bright 
and  handsome  calf.  Figure  5,  taken  October  16,  shows  the  animal 


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FIG.  10.— Curve  of  weight  of  calf  No.  68. 

when  it  had  all  the  typical  symptoms  of  loco  poisoning.  On  October 
18  it  was  down  in  the  pasture,  and  remained  down  in  the  same  position 
until  its  death  on  October  20.  During  this  time  an  attempt  was 
made  to  feed  and  water  it,  but  without  success.  Figure  6  shows  the 
attitude  assumed  by  the  animal  during  the  last  stages. 

This  was  also  a  particularly  interesting  case,  as  the  calf  was  born 
of  a  mother  that  was  eating  loco,  learned  the  habit  from  its  mother, 
and  gradually  succumbed  to  the  disease. 


EXPERIMENTS  WITH   HORSES,   1906. 


63 


It  is  of  interest  to  compare  this  calf  with  another,  No.  68,  that  was 
born  about  a  month  later.  No.  68  was  kept  in  the  loco-free  pasture 
through  the  whole  summer.  It  soon  outstripped  No.  67  in  weight, 
and  at  the  end  of  the  summer  was  a  strong,  healthy  calf,  weighing 
350  pounds.  The  curves  of  weight  of  Nos.  67  and  68  are  given  in 
figures  9  and  10. 

EXPERIMENTS    WITH    HORSES. 

A  few  of  the  cases  among  the  horses  in  1906  deserve  special  notice 
as  being  typical  of  the  general  results  of  loco  feeding. 

Case  16. — This  horse  had  been  in  the  loco-free  pasture  during  the 
season  of  1905  and  until  June  11,  1906.  From  that  time  on  it  was 
fed  Astragalus  mollissimus  and  hay.  At  first  the  amount  of  hay  was 
very  small  in  order  to  induce  it  to  eat  more  of  the  loco,  but  later  on 
the  amount  of  hay  was  increased,  so  that  there  might  be  no  question 
in  regard  to  the  possibilities  of  starvation.  The  animal  was  kept 


650 


600 


1906     MJY 


JULY 


SEPT.    1906 


FIG.  11. — Curve  of  weight  of  horse  No.  16. 

upon  this  diet  until  July  21.  During  this  time  it  lost  in  weight  about 
60  pounds.  It  was  noticed  that  it  ate  the  loco  in  a  very  variable 
manner;  sometimes  very  little  and  at  other  times  very  freely.  On 
July  22,  as  it  had  become  impossible  to  ob.tain  suHicient  of  the  Astra- 
galus mollissimus,  the  horse  was  put  in  the  AragaUus  himberti  pasture, 
remaining  there  until  July  31,  when  it  was  taken  in  from  the  pasture 
and  fed  AragaUus  lamberti  and  hay.  This  diet  was  kept  up  until 
September  19,  when  tho  horso  was  taken  up  for  treatment,  but  it 
continued  to  grow  worse  and  died  September  25. 

In  this  cose  there  was  decided  trouble  with  the  lungs  as  well  as  the 
ordinary  loco  symptoms.  Plate  VIII,  figures  1  and  2,  show  the 
effect  of  the  loco  upon  the  animal.  The  curve,  figure  11,  shows  the 
loss  in  weight. 

Case  50. — This  was  an  old  horse  that  had  evidently  been  worked 
for  many  years.  It  was  received  in  the  spring  of  1906,  and  on 
arrival  at  the  station  was  very  poor,  weighing  only  670  pounds.  It 


64 


THE   LOCO-WEED    DISEASE    OF   THE   PLAINS. 


was  placed  in  the  Aragallus  lamberti  pasture  and  immediately  com- 
menced to  eat  more  or  less  of  the  loco  plant.  It  gained  somewhat  in 
weight,  weighing  695  pounds  on  July  18.  Plate  VIII,  figure  5,  shows 
its  condition  at  this  time.  On  September  7,  however,  it  weighed 
only  660  pounds,  having  lost  a  good  deal  of  flesh.  It  continued  to 
eat  AragaUus  lamberti  until  September  16.  On  this  date  it  disap- 
peared from  the  station  and  was  located  several  miles  away,  and  the 
attempt  to  drive  it  in  brought  out  the  fact  that  it  was  not  only  poor 
but  very  badly  locoed  in  every  way.  It  was  blind  in  one  eye,  proba- 
bly having  received  the  injury  by  running  into  a  barbed-wire  fence. 
It  would  walk  directly  into  a  fence,  not  stopping  until  actually  cut 
by  the  wire.  When  driven,  it  would  turn  to  one  side  and  then  move 
straight  ahead,  not  stopping  until  it  ran  against  a  fence.  In  order 
to  turn  the  animal  it  was  necessary  not  only  to  get  in  front  of  it,  but 
to  strike  it  over  the  head.  It  was  very  poor  at  this  time,  but  seemed 
to  have  a  good  deal  of  strength.  On  September  17  it  was  driven  out, 


FIG.  12.— Curve  of  weight  of  horse  No.  50. 

but  showed  no  sense  of  direction  whatever  in  regard  to  the  place  it 
should  go.  Plate  VIII,  figure  6,  shows  its  condition.  The  picture 
also  shows  very  clearly  the  cuts  upon  its  head  which  had  been  caused 
by  running  into  a  barbed-wire  fence. 

An  attempt  was  made  to  treat  the  animal,  but  without  any  effect. 
On  the  morning  of  September  19  it  was  found  dead.  It  had 
broken  through  three  corral  fences  and  had  fallen  down  into  a  hole 
which  had  been  dug  for  a  cellar.  Although  the  animal  was  old  it  was 
nevertheless  strong,  and  in  the  early  part  of  the  season  was  in  very 
good  condition.  Its  end  was  doubtless  due  to  the  effect  of  the  loco. 
Figure  12  gives  the  curve  of  its  weight. 

Case  52. — This  was  of  interest  as  being  one  of  the  few  cases  of 
mules  experimented  upon.  The  animal  was  put  in  the  Aragallus 
lamberti  pasture  early  in  the  spring  of  1906  and  at  first  apparently 
ate  none  of  the  loco.  Toward  the  end  of  May,  however,  some  two 
weeks  after  it  had  been  placed  in  the  pasture,  it  was  noticed  that  it 
not  only  ate  AragaUus  lamberti  freely,  but  seemed  to  care  for  nothing 


EXPERIMENTS  WITH   HOESES,   1906. 


65 


else.  At  this  time  it  would  pick  off  the  leaves,  but  would  not  eat  the 
flowers.  It  passed  from  one  plant  to  another,  eating  them  with  great 
greediness.  On  June  18  it  was  weighed  and  found  to  weigh  590 
pounds,  a  gain  of  40  pounds  from  the  time  it  was  placed  in  the  pas- 
ture. When  weighed  on  September  7,  heavy  loss  was  shown,  as  it 
then  weighed  only  505  pounds.  The  mule  was  kept  in  the  AragaUus 
lamberti  pasture,  but  it  was  noticed  on  September  13  that  it  was  not 
eating  at  all.  Rather  to  our  surprise,  on  the  morning  of  September 
15  it  was  found  dead.  It  was  thin,  but  nevertheless  seemed  to  be 
quite  strong.  Plate  VIII,  figure  3,  shows  its  condition  in  the  spring, 
when  the  experiment  commenced;  figure  4,  September  7,  shows  its 
peculiar  attitude,  with  all  the  symptoms  of  loco  poisoning  very 
marked.  Text  figure  13  gives  the  curve  of  weight. 

Case  59. — This  mare  was  placed  in  the  loco-free  pasture  during  the 
early  part  of  the  season.     She  was  about  8  years  old  and  never  had 


I 

600 
550 
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1906   MAY 

JUNE 

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FIG.  13. — Curve  of  weight  of  horse  No.  52. 

been  broken.  She  had  a  peculiar  congenital  malformation  of  the 
fetlock  joints.  Except  for  this  defect,  however,  she  was  entirely 
sound  and  healthy.  She  increased  in  weight,  and  when,  on  July  18, 
she  was  placed  in  the  Aragattus  lamberti  pasture  she  weighed  885 
pounds.  On  September  7  she  weighed  830  pounds.  During  this 
time  she  ate  comparatively  little  of  the  AragaUus  lamberti,  and  on 
September  18  she  was  taken  into  the  corrals  in  order  to  hasten  the 
effect  of  poisoning  by  forced  feeding  of  Araqallus  lamberti  and  hay. 
This  feeding  was  continued  until  October  20,  when  for  about  a  week 
she  was  in  the  Aragattus  lamberti  pasture.  On  the  2Sth  it  was  noted 
that  she  was  getting  exceedingly  poor  and  that  the  nervous  symp- 
toms were  very  marked.  From  that  time  on  she  was  kept  in  the 
corral,  fed  hay  and  chop,  and  was  treated,  the  treatment  continuing 
through  October  and  November  with  no  apparent  effect.  This  loss  of 
flesh  was  particularly  noticeable,  because  when  she  was  taken  into  the 
corral  to  commence  the  feeding  of  loco  she  was  an  especially  smooth, 
79154—  Bull.  112—09 5 


66 


THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 


handsome-looking  animal,  and  the  loco  effect  came  very  quickly  and 
in  a  very  marked  way.  She  was  taken  to  Fort  Collins  in  December 
in  order  to  continue  the  treatment  during  the  winter,  but  died  on 
the  road.  This  was  a  typical  loco  case,  the  symptoms  were  marked 
and  distinct,  and  the  case  is  particularly  interesting  because  the 
effect  of  the  poison  came  in  such  a  short  time.  Text  figure  14  shows 
the  curve  of  weight. 

EXPERIMENTS    WITH    SHEEP. 

Through  the  kindness  of  local  sheep  owners  near  Hugo  considerable 
work  on  sheep  was  possible  during  the  season  of  1906.  These  sheep 
were  numbered  as  received  and  were  kept  in  the  corral  nights  and 
herded  in  the  neighborhood  of  the  experimental  ranch  and  on  a  pas- 
ture which  was  pretty  well  covered  with  Aragallus  lamberti.  Some 
of  the  sheep  were  very  weak  when  received  and  in  bad  general  condi- 


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FIG.  14.— Curve  of  weight  of  horse  No.  59. 

tion.  During  the  season  69  were  used  in  the  experiment,  63  being 
bucks  a  year  old  and  6  lambs.  All  were  supposed  to  be  locoed  at  the 
time  when  they  were  received. 

In  the  early  autopsies  special  attention  was  paid  to  the  presence 
of  parasites,  particularly  the  grubs  of  (Estrus  ovis.  The  symptoms  of 
this  disease  (grub  in  the  head)  are  very  similar  to  'the  symptoms  of 
loco,  and  there  was  a  possibility  that  the  so-called  locoed  sheep  were 
not  locoed,  but  were  affected  by  this  parasite.  Thysanosoma  actini- 
oides  was  also  found  in  greater  or  less  numbers  in  the  duodenum  or 
in  the  bile  ducts,  or  in  both. 

Inasmuch  as  in  the  former  investigations  on  locoed  sheep  under 
the  direction  of  Doctor  Marshall,  a  partial  report  of  which  was  made 
in  the  Johns  Hopkins  Hospital  bulletin,  the  very  definite  conclusion 
was  reached  that  so-called  locoed  sheep  were  infested  by  these  two 
parasites,  and  that  if  the  parasites  were  removed  the  cause  of  the 
trouble  would  also  be  removed,  these  early  autopsies  were  particu- 
larly interesting. 


BUL.  112,  BUREAU  OF  AMMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  VIII. 


Case  16,  June  6,  1906.     Horse  before  eating  loco 
weed. 


Case  16,  September  15,  1906.  Animal  shown  in 
Fig.  1,  in  an  advanced  stage  of  loco  poisoning, 
emaciated  and  extremely  weak. 


Case  52,  May  I't,  1V06.      Mule  in  fairly  good  con- 
dition before  feeding  upon  loco  weed. 


Case  52,  September  7, 1906.     Mule  shown  in  Fig.  3, 
in  last  stages  of  loco  poisoning. 


Case  50,  July  IV,  1V06.     An  old  horse  before  being 
fed  with  the  loco  weed. 


Case  50,  September  IN.  1'W).  Same  animal  as  in 
Fig.  5,  showing  effect  of  loco  poisoning  in  atti- 
tude and  emaciated  condition  ;  also  shows  cuts 
produced  by  running  into  barbed  wire  fence. 


BUL.    112,   BUHEAU  OF  ANIMAL  INDUSTRY,   U.    S.    DEPT.  OF  AGRICULTURE. 


PLATE  IX. 


A  group  of  locoed  sheep,   showing  the  general 
appearance  of  locoed  animals. 


Sheep  27.     A  locoed  sheep  in  last  stages  of 
poisoning. 


Sheep  36.     Effect  of  loco  poisoning  combined  with 
grub  in  the  head. 


Same  as  Fig.  3,  in  a  different  attitude. 


Case  66,  October  20,  1906.     A  locoed  lamb. 


Case  66,  November  12. 1<X)6.     Attitude  of  the  ani- 
mal just  before  its  death. 


EXPERIMENTS   WITH   SHEEP,   1906.  67 

If  the  sheep  were  affected  with  loco  poisoning  it  was  evident  that 
the  effect  of  the  loco  was  complicated  by  the  parasites,  and,  of  course, 
it  might  be  possible  that  the  primary  trouble  was  not  poison  by  loco 
plants,  but  the  effect  of  these  parasites.  It  therefore  seemed  desir- 
able, if  possible,  to  remove  the  parasites,  and  thus  do  away  with  the 
sources  of  complication.  In  this  work  of  removal,  however,  the 
results  proved  that  we  were  only  partially  successful. 

Five  of  the  sheep  were  given  gasoline  and  milk  as  a  vermifuge. 
Three  of  these  were  autopsied,  with  the  result  that  one  was  found 
with  many  tapeworms,  the  other  two  with  a  few.  It  would  appear, 
then,  that  the  work  of  the  vermifuge  was  only  partially  successful. 
It  may  have  reduced  the  number  of  tapeworms,  but  it  certainly  did 
not  clean  them  all  out. 

Four  sheep  were  treated  for  (Estrus  ovi*.  In  two  of  these,  holes 
were  drilled  into  the  frontal  sinuses,  and  about  a  teaspoonful  of  gaso- 
line injected  into  each  side;  they  were  then  washed  out  with  a  foun- 
tain syringe  with  water  containing  a  little  gasoline.  Of  these  two, 
one  was  operated  upon  on  May  10  and  died  August  IS,  when  there 
were  still  some  individuals  of  (Estrus  ovis  in  the  frontal  sinuses. 
The  other  was  operated  upon  on  May  0  and  died  the  21st,  at  which 
time  8  living  grubs  and  several  dead  ones  were  taken  out  of  the  frontal 
sinuses  and  nostrils.  Inasmuch  as  during  the  operation  of  washing 
out  a  considerable  number  of  (Estrus  ovis  were  seen  to  come  from  the 
nostrils,  it  is  known  that  the  operation  was  partially  successful.  It 
would  appear,  however,  that  in  neither  case  did  it  entirely  rid  the 
animals  of  the  grubs. 

The  other  two  cases  were  treated  by  injecting  gasoline  into  (he 
nostrils.  In  neither  of  these,  unfortunately,  were  we  able  to  make 
autopsies,  so  that  the  result  of  the  experiment  was  not  known. 

A  similar  experiment  was  tried  on  some  sheep  in  the  season  of 
1007.  Sheep  Nos.  74,  77,  and  SO  were  treated  by  injection  of  about 
a  teaspoonful  of  gasoline  into  each  nostril.  One  of  these  was  later 
killed  by  a  coyote.  It  was  autopsied  and  no  grubs  were  found  in  the 
frontal  sinuses.  Inasmuch  as  we  feel  certain  of  the  diagnosis  of 
grub,  it  would  seem  that  in  this  ease  the  treatment  with  gasoline  was 
successful.  Of  the  two  others,  No.  77  was  in  bad  condition  when 
treated,  but  immediately  began  to  get  better.  No.  SO  was  also  in 
better  condition  after  treatment.  It  seems  probable  that  in  all  these 
cases  the  gasoline  treatment  for  (ExtniM  on*  was  successful. 

Soon  after  the  first  lot  of  bucks  was  received  in  1(M)(>  an  experi- 
ment was  made  to  see  whether  they  would  eat  loco  readily  or  not. 
Hay  mixed  with  Anifjnllux  lamberti  was  placed  in  the  corral  where 
the  sheep  were  confined.  It  was  noticed  that  1'J  of  them  would  eat 
the  weed  to  some  extent.  None  of  them  ate  very  greedily,  but 


68  THE   LOCO-WEED    DISEASE    OF   THE   PLAINS. 

they  would  pass  by  the  pile,  perhaps  pick  up  a  single  plant,  and  then 
pick  up  more  hay.  The  others  did  not  eat  the  plant  at  all.  This  pre- 
liminary experiment  seemed  to  show  that  none  were  anxious  to  eat 
the  loco  and  that  many  did  not  care  to  eat  it  at  all.  As  the  season 
went  on,  however,  all  of  them  ate  more  or.  less  of  the  Aragdllus  lam- 
berti  in  the  field,  sometimes  eating  a  considerable  amount  and  at 
other  times  only  eating  a  little.  Inasmuch  as  sheep  have  a  way  of 
nibbling  at  anything,  it  was  sometimes  rather  difficult  to  tell  whether 
they  had  a  real  passion  for  the  weed  or  not.  There  were  some, 
however,  that  would  go  from  plant  to  plant  and  devote  themselves 
for  at  least  a  portion  of  the  day  to  eating  nothing  at  all  except  Ara- 
gallus  lamberti.  It  was  also  rather  difficult  to  tell  to  what  extent  the 
animals  were  affected  by  the  weed.  Many  of  them  were  rather  poor 
and  weak.  Some  of  them  were  more  or  less  erratic  in  their  move- 
ments, and  as  the  season  went  on  this  became  more  pronounced.  In- 
stead of  keeping  together  in  a  bunch  as  normal  sheep  do,  they  would 
scatter  in  groups  of  two  or  three,  while  sometimes  a  single  animal 
would  stray  off  by  himself.  It  thus  became  increasingly  difficult 
to  care  for  them  properly,  as  it  was  impossible  to  keep  a  herder 
with  them  all  the  time.  Sometimes  some  of  them  would  be  lost  for 
a  day  or  two,  and  some  disappeared  never  to  return,  having  fallen 
prey  to  the  coyotes. 

Plate  IX,  figure  1,  shows  the  general  character  of  the  sheep 
received  from  Mr.  Mclntyre  in  the  spring.  The  cases  all  resem- 
bled each  other  very  closely.  Attention,  perhaps,  may  be  called  to 
two  or  three  of  them,  with  the  accompanying  illustrations,  as  show- 
ing the  typical  condition  of  locoed  sheep. 

Sheep  27. — This  was  badly  locoed  when  received  and  lived  only  a 
few  days.  Attention  is  called  to  it  because  the  picture  (PI.  IX,  fig.  2) 
shows  the  typical  appearance  of  a  locoed  sheep  in  the  last  stages  of 
the  disease. 

Sheep  36. — This  was  interesting  as  being  an  animal  upon  which  an 
operation  was  performed  to  rid  it  of  (Estrus  oms.  There  seems  no 
question  that  the  operation  was  partially  successful,  although  not 
completely  so.  The  sheep  was  an  old  buck,  perhaps  5  or  6  years 
old,  and,  except  for  his  emaciation,  was  rather  a  handsome  animal. 
He  was  kept  about  a  month,  when  he  died,  his  death  without  any 
doubt  being  the  result  of  the  loco  poison.  Plate  IX,  figures  3  and  4, 
show  the  condition  of  the  animal. 

Lamli  66. — In  Plate  IX,  figures  5  and  6,  are  shown  the  peculiari- 
ties of  locoed  lambs.  This  was  a  lamb  received  in  October,  and  was 
badly  locoed.  As  the  picture  shows,  the  animal  was  in  good  condi- 
tion so  far  as  flesh  was  concerned.  However,  it  was  weak,  stagger- 
ing about  in  typical  loco  fashion.  Plate  IX,  figure  6,  shows  the  dull, 
dozy  condition  of  the  animal,  the  photograph  having  been  taken 
only  a  short  time  before  its  death. 


EXPERIMENTS   WITH   SHEEP^    1906.  69 

In  1907,  besides  a  locoed  wether  presented  by  the  Hamp  Brothers, 
we  had  15  bucks  brought  in  by  Mr.  Mclntyre  on  June  17.  The  his- 
tory of  these  15  bucks  was  of  special  interest  because  it  differed  sc 
much  from  that  of  the  sheep  brought  in  by  the  same  owner  the 
preceding  year.  When  they  were  delivered  at  the  experiment  sta- 
tion they  were  all  poor,  some  of  them  staggering  more  or  less  as  they 
walked,  and  they  were  considered  by  the  owner  and  other  sheepmen 
who  saw  them  as  typical  specimens  of  locoed  sheep.  They  resem- 
bled in  their  general  appearance  very  closely  the  sheep  that  were  used 
for  experiment  in  1906.  From  the  very  beginning,  however,  their 
behavior  was  different.  While  those  of  1906  would  feed  where  loco 
was  abundant,  confining  their  pasturage  very  largely  to  such  localities, 
those  of  1907  sought  the  lower  land,  where  there  was  no  loco  but  more 
grass,  and  even  when  the  loco  was  abundant  about  them  they  paid 
very  little  attention  to  it.  While  the  sheep  of  1906  would  scatter, 
going  off  in  groups  of  two  or  three  or  individually,  those  of  1907  kept 
together  and  behaved  more  like  normal  animals.  They  were  fed  a 
little  grain  daily,  mainly  to  accustom  them  to  have  a  habit  of  coming 
to  the  corrals  at  night,  but  not  enough  to  make  any  great  difference 
in  the  formation  of  flesh.  Nearly  all  of  them  gained  through  the 
summer,  and  were  returned  to  the  owner  in  good  condition. 

A  few  of  these  sheep,  as  explained  elsewhere,  were  treated  for 
(Esirus  ovis.  Most  of  them  had  discharges  from  the  nose,  in  many 
cases  bloody,  and  it  is  possible  that  the  real  trouble  with  the  band 
was  not  loco  but  the  grubs  of  (Estrus  ovis.  As  is  well  known,  animals 
generally  recover  from  attacks  of  this  grub,  and  it  may  be  that  the 
improvement  of  the  sheep  in  question  was  due  to  the  loss  of  the 
grubs  in  the  course  of  the  summer. 

There  is  no  doubt  that  nearly  all  of  the  sheep  which  were  kept  at 
the  ranch  in  1906  were  locoed,  and  just  as  little  that  few  if  any  of 
the  band  received  in  1907  were  affected  by  the  loco  poison.  The 
experiments  with  sheep  were,  therefore,  of  particular  interest  us 
showing  how  easily  the  effects  of  grub  in  the  head  ma}'  be  confused 
with  loco  poisoning.  Incidentally,  it  would  appear  from  our  work 
that  the  injection  of  gasoline  into  the  nostrils  of  sheep  that  are 
infested  with  the  grub  of  (Estrus  ovin  is  likely  to  be  followed  with 
excellent  results. 


DI8CUMION   OK  THK   SHKKP   EXPERIMENTS. 


Sixty-three  of  the  69  sheep  used  in  the  experiment  of  1906  were 
bucks  a  year  old  or  more,  and  6  were  lambs.  All  were  supposed  to  be 
locoed  when  they  were  received.  Autopsies  were  held  upon  33  of  the 
cases.  In  the  autopsies  special  attention  was  paid  to  the  presence 
of  parasites  because  of  the  conclusions  reached  by  Doctor  Marshall, 
which  have  already  been  summarized  in  the  discussion  of  the  lit- 
erature. Of  the  33  on  which  autopsies  were  held,  23  had  grubs  of 


70  THE  LOCO- WEED   DISEASE   OF  THE  PLAINS. 

(Estrus  ovis.  These  were  present  in  some  cases  in  considerable 
numbers,  and  their  presence  was  indicated  before  death  by  a  bloody 
discharge  from  the  nostrils.  One  case,  No.  23,  was  considered  to  have 
died  as  the  result  of  the  presence  of  this  grub.  Twenty- three  of  the 
33  were  infected  with  TJiysanosoma  actinioides.  In  most  cases, 
however,  this  tapeworm  was  not  present  in  large  numbers.  In 
some  the  bile  ducts  were  much  distended  with  them,  but  commonly 
the  numbers  were  rather  small,  and  perhaps  not  more  than  would 
be  expected  in  an  animal  which  is  so  subject  to  parasitic  infection. 
Cysticerci  were  found  in  6  of  the  cases,  but  there  is  no  reason  to  think 
that  they  affected  the  animals  injuriously.  In  13  of  the  post-mortem 
cases  the  inner  walls  of  the  fourth  stomach  were  inflamed;  9  had 
blood  clots  in  the  lateral  ventricles;  15  had  an  apparently  abnormal 
number  of  hemolymph  glands  in  the  dorsal  parts  of  the  thorax,  or 
the  abdominal  cavity,  or  both,  and  in  18  there  was  a  serous  coagulum 
present  in  the  epidural  space  of  the  spinal  canal. 

In  the  experiment  of  1907  most  of  the  sheep  were  not  seriously 
affected  by  the  loco  poison,  but  were  suffering  from  other  causes,  the 
evidence  tending  to  show  that  the  presence  of  (Estrus  ovis  was  in 
part  at  least  responsible  for  their  condition.  The  principal  diffi- 
culty with  most  of  the  animals  in  1906  was  the  loco  poison,  with 
the  effects  complicated  by  parasites.  On  the  other  hand,  it  seems 
that  the  chief  trouble  with  most  of  the  sheep  in  1907  was  caused  by 
the  parasites  and  that  the  loco  had  little  if  anything  to  do  with  their 
condition.  It  is  evident  from  our  work  that  it  is  very  easy  to  confuse 
the  effects  of  parasites  with  those  of  loco  poisoning.  The  general 
appearance  of  the  bands  of  sheep  in  1906  and  1907  was  the  same, 
and  not  only  the  author,  but  experienced  sheepmen,  declared  that 
both  bands  were  locoed.  In  the  majority  of  cases  it  was  only  by 
post-mortem  examination  that  the  diagnosis  could  be  confirmed. 
These  statements  refer,  of  course,  to  the  general  symptoms.  If  the 
habits  of  the  sheep  are  observed  there  is  a  marked  difference.  The 
sheep  affected  with  (Estrus  ovis,  except  when  they  are  in  very  bad 
condition,  keep  together  like  normal  animals,  and  show  a  preference 
for  good  food,  although  they  may  at  times  eat  loco.  The  locoed 
sheep,  on  the  other  hand,  are  more  erratic,  and  develop  a  solitary 
habit  to  a  greater  or  less  extent.  They  show,  too,  a  marked  fondness 
for  the  loco  weed.  At  the  same  time,  when  one  is  dealing  with  a  con- 
siderable number  of  sheep,  it  is  a  matter  of  much  difficulty  to  separate 
the  locoed  animals  from  those  affected  with  grub  in  the  head.  It  is 
not  strange  that  in  experiments  where  sheep  only  have  been  used 
those  in  charge  have  been  led  to  the  belief  that  the  so-called  locoed 
sheep  are  sheep  infested  with  parasites,  for  the  symptoms  bear  a 
close  resemblance.  Moreover,  it  is  very  possible  that  in  individual 
experiments  the  supposed  locoed  sheep  were  in  fact  not  locoed  at  all. 


EXPERIMENT   AT   WOODLAND   PARK,   COLO.  71 

It  is  a  matter  of  considerable  interest  that  lambs  are  much  more 
quickly  affected  than  older  animals.  Attention  was  first  called  to 
this  fact  by  Mr.  A.  Mclntyre,  who  stated  that  lambs  would  frequently 
succumb  to  the  poison  in  two  or  three  weeks,  and  with  little  loss  of 
flesh.  The  author's  observations  were  completely  confirmatory  of 
this  statement.  Of  the  6  lambs  under  observation  (Nos.  65  to  70), 
all  were  in  good  flesh,  but  very  distinctly  locoed.  Post-mortems 
were  held  on  5  of  these,  and  the  results  were  very  interesting.  All 
had  clots  in  the  lateral  ventricles.  All  had  serous  coagulum  in  the 
spinal  canal,  and  all  had  congested  walls  of  the  fourth  stomach. 
This  would  seem  to  confirm  our  opinion  that  these  lesions  are  charac- 
teristic of  the  locoed  condition,  but  that  in  chronic  cases  they  may  be 
more  or  less  masked. 

EXPERIMENT    AT    WOODLAND    PARK,  COLO. 

The  loco  conditions  were  so  different  in  the  mountains  that  it 
seemed  wise  to  conduct  a  feeding  experiment  to  determine  to  what 
extent  the  phenomena  would  differ  from  those  in  the  plains.  The 
loco  plants  grow  in  the  mountains  to  an  elevation  of  8,000  to  10,000 
feet,  and  among  the  stockmen  pasturing  horses  and  cattle  in  these 
localities  there  are  plenty  of  stories  of  locoed  animals.  The  prin- 
cipal loco  plant  in  the  region  where  the  experiment  was  carried  on  is 
Aragallus  lamberti,  but  with  this  are  associated  a  great  many  plants  of 
Astragalus  nitidus  and  a  smaller  number  of  Astragalus  splendem.  In 
the  summer  of  1906  land  was  offered  for  an  experiment  between 
Woodland  Park  and  Divide,  on  the  Colorado  Midland  Railroad.  A 
particularly  thick  field  of  loco  was  fenced  in  for  a  loco  pasture,  and  an 
adjoining  piece  with  very  little  loco  was  used  as  a  control  pasture. 
Eleven  horses  and  12  head  of  cattle  were  used  in  this  experiment, 
6  of  the  cattle  being  donated  by  the  Crescent  Cattle  Company,  of 
Cripple  Creek. 

The  horses  were  put  in  the  pasture  July  13 — 6  in  the  loco  pasture 
and  5  in  the  control  pasture.  A  week  later  6  head  of  cattle  were 
received  and  were  divided,  one-half  being  put  in  each  pasture.  On 
July  27  horses  73  and  74  were  taken  into  the  corral,  where  they  were 
kept  through  the  rest  of  the  season,  and  fed  on  cut  loco,  with  an  abun- 
dance of  hay.  On  August  14,  6  more  cows  were  received  and  were 
divided  between  the  two  pastures.  The  cattle  ate  loco  readily,  and 
before  the  season  was  over  cleaned  out  the  pasture  pretty  thoroughly. 
The  horses  would  not  eat  loco  in  the  field,  but  those  in  the  corral  ate 
quite  freely.  None  of  the  cattle  showed  any  positive  effects  as  the 
result  of  the  loco  eating.  The  horses  in  the  corral  grew  thinner, 
became  dull,  and  showed  a  somewhat  stiffened  gait.  The  lack  of  more 
general  results  in  this  feeding  experiment  was  due  in  part  probably 
to  the  comparatively  short  time  during  which  the  experiment  was 


72  THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 

carried  on.  It  was  unfortunate  that  we  were  unable  to  install  the 
experiment  earlier  in  the  season. 

The  animals  remaining  in  the  fall  of  1906  were  taken  to  the  ranch 
of  the  Crescent  Cattle  Company,  where  they  were  kept  during  the  win- 
ter, receiving  the  ordinary  treatment  of  the  range  stock  owned  by  that 
company.  During  the  winter  horses  73  and  74  died,  their  death 
doubtless  being  occasioned  by  the  weakness  produced  by  the  loco 
poison  during  the  preceding  summer. 

In  1907,  8  horses  and  8  cattle  were  pastured  at  Woodland  Park; 
part  of  these,  as  in  the  preceding  season,  were  kept  in  the  loco  pasture 
and  part  in  another  past  -,  Comparatively  free  from  loco.  It  was 
found,  however,  as  the  season  progressed,  that  the  so-called  loco-free 
pasture  had  considerable  of  the  plant  in  it,  and  some  of  the  animals 
which  were  pastured  in  it  became  locoed  in  spite  of  the  small  tempta- 
tion. As  in  the  preceding  season,  we  were  unfortunate,  because  of  a 
series  of  events  entirely  beyond  our  control,  which  made  it  impossible 
to  start  the  real  experiment  until  comparatively  late. 

The  animals  ate  the  loco  readily,  but  none  of  the  cattle  were  clearly 
locoed.  Horse  76  was  put  in  the  loco  pasture  on  June  11,  and  was 
badly  locoed  on  August  6.  This  locoed  condition  was  evident  in  her 
extremely  nervous  manner.  She  was  easily  startled  and  ate  in  a 
nervous  way,  as  if  frightened.  She  had  the  high  step  peculiar  to 
locoes  and  the  straddling  attitude  of  the  hind  legs  when  she  walked, 
and  would  rear  when  startled.  At  this  time,  however,  there  was  no 
loss  of  flesh,  but  toward  the  end  of  August  she  showed  a  distinct  loss 
of  flesh,  and  on  August  31  was  taken  up  for  treatment,  the  result  of 
which  is  given  elsewhere. 

At  the  end  of  the  season  the  stock  was  taken  to  Hugo  to  be  pas- 
tured during  the  winter.  At  this  time  5  of  the  8  horses  were  dis- 
tinctly locoed,  but  none  of  the  cattle  showed  the  effects  of  the  poison. 

The  principal  result  of  the  two  years'  feeding  at  Woodland  Park 
seemed  to  indicate  that  stock  is  not  as  easily  locoed  in  the  mountains 
as  in  the  plains,  and  that  horses  are  much  more  easily  locoed  than 
cattle.  The  latter  fact  seems  to  be  in  harmony  with  the  results  of 
experience,  for  there  are  very  few  complaints  of  locoed  cattle  in  the 
mountains.  A  number  of  factors  may  explain  the  smaller  number  of 
locoed  horses  in  the  mountains.  The  loco  is  not  so  abundant  as  in 
the  plains,  commonly  being  restricted  to  smaller  areas,  while  the  grass 
is  more  abundant  and  commonly  does  not  dry  out,  as  it  does  on  the 
plains,  so  that  the  animals  are  not  forced  upon  the  loco  because  of 
lack  of  other  food.  It  is  very  possible,  too,  that  the  amount  of  the 
poison  in  the  mountain  loco  is  not  as  great  as  in  the  plants  of  the 
plains.  This  can  only  be  determined  by  extensive  laboratory  experi- 
ments, for  which  thus  far  there  has  been  no  opportunity. 


REMEDIAL    MEASURES.  73 

'    EXPERIMENT    AT    IMPERIAL,    NEBR. 

This  experiment  was  carried  on  in  cooperation  with  the  experiment 
station  of  the  University  of  Nebraska,  which  was  represented  in  this 
work  by  Dr.  A.  T.  Peters.  The  work  was  located  at  Imperial,  in  the 
southwestern  part  of  Nebraska,  and  the  animals  for  the  experiment 
were  donated  by  local  stockmen.  The  loco  in  this  section  consists 
almost  entirely  of  Astragalus  moTlissimus.  The  work  was  under  the 
immediate  supervision  of  Mr.  L.  B.  Sturdevant,  of  the  University  of 
Nebraska. 

In  this  feeding  experiment  the  attempt  was  made  to  get  results  from 
the  loco  as  rapidly  as  possible.  With  this  end  in  view  the  animals 
were  herded  on  the  loco  part  of  the  time,  and  part  of  the  time  the 
weed  was  cut  and  fed  to  them.  In  the  feeding  experiments  hay  was 
always  used  as  well  as  the  loco,  in  order  that  there  might  be  no  ques- 
tion of  starvation.  The  work  was  started  about  July  4  and  was  car- 
ried on  to  the  end  of  October,  when  all  the  animals  eating  loco  were 
dead.  Only  horses  were  used  in  this  experiment,  and  the  number  was 
unfortunately  much  too  small.  All  contracted  the  disease,  however, 
and  died  with  the  typical  symptoms  of  locoed  animals,  showing  the 
same  post-mortem  phenomena  as  were  exhibited  in  the  animals 
studied  in  Colorado.  Careful  post-mortems  were  made,  and  the  gen- 
eral results  of  the  work  served  to  confirm  that  carried  on  at  Hugo. 
Tli us  the  work  in  Colorado  was  supplemented  in  an  important  way, 
for  it  was  impossible  during  the  season  of  1906  to  obtain  in  the  neigh- 
borhood of  Hugo  very  much  of  the  Astragalus  moUissimus  for  feeding 
experiments. 

REMEDIAL  MEASURES. 

In  the  work  of  the  first  season  no  attempt  was  made  to  experiment 
with  remedies  for  the  loco  disease.  The  knowledge  of  the  subject 
was  so  indefinite  that  there  seemed  to  be  no  adequate  foundation  for 
such  work.  It  seemed  better  to  devote  all  our  energies  to  getting  a 
diagnosis  of  the  disease  and  determining  its  cause  before  attempting 
to  apply  any  remedies. 

During  the  second  season,  however,  it  appeared  that  tho  correct 
diagnosis  of  the  disease  was  gradually  being  evolved  as  the  result  of 
our  observations,  and  it  seemed  best  to  make  some  tentative  experi- 
ments with  remedies.  Inasmuch  as  most  locoed  animals  are  con- 
stipated, it  was  clear  that  something  to  produce  free  action  of  the 
l>owels  was  of  first  importance.  This  would  be  true  not  only  be- 
cause it  was  desirable  to  have  healthy  action  of  the  intestines,  but 
l>ccause  it  would  be  presumed  that  a  free  action  of  the  bowels  would 
aid  in  eliminating  whatever  poison  had  boon  absorbed.  Tho  remedy 
used  for  this  condition  of  constipation  was  magnesium  sulphate. 


74  THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 

When  this  was  first  used,  the  chemistry  of  the  loco  plant  had  not 
been  worked  out,  and  the  reason  for  its  use  was  simply  to  correct 
constipation.  As  it  turned  out  later  from  the  laboratory  work, 
in  this  substance  we  were  using  the  most  probable  antidote  for 
the  barium  poison.  This  information,  however,  came  too  late  to 
make  it  possible  to  experiment  with  antidotes.  It  would  seem  pos- 
sible to  arrange  to  give  small  doses  of  a  sulphate  which  should 
neutralize  the  effects  of  the  extremely  small  amounts  of  barium 
in  the  loco.  Doctor  True  has  suggested  that  this  might  be  done  in 
connection  with  salting  the  stock.  It  may  be  that  through  the  food 
or  drink  it  will  be  possible  to  give  enough  of  an  antidote,  so  that 
whatever  effect  the  barium  has  may  be  nullified.  Further  experi- 
ments to  this  end  will  be  made. 

The  effects  of  loco  poisoning  come  on  very  slowly  as  a  rule  and  after 
a  long  period  of  feeding.  This  period  may  not  only  be  many  days, 
but  frequently  months,  and  in  some  cases  even  years.  The  locoed 
condition  seems  to  be  the  accumulated  effect  of  a  multitude  of  small 
doses  of  the  poison,  and  the  cure  of  the  animals  would  most  probably 
be  sought  in  a  treatment  of  the  general  condition  of  the  animal  rather 
than  in  any  special  treatment  to  counteract  the  effects  of  the  poison. 
The  most  marked  symptoms  of  locoed  animals  are  the  nervous  phe- 
nomena and  the  anemia.  These  conditions  were  those  that  were 
especially  considered  in  planning  remedies.  It  seemed  wise  to  pay 
more  attention  to  building  up  the  animals  than  to  attempt  to  use  an 
antidote.  Several  remedies  were  used  which  were  clearly  proved  to 
be  useless.  One  of  these  was  potassium  iodid,  with  which  a  fairly 
thorough  trial  was  made.  Asafetida,  valerian,  and  caffein  were 
tried,  but  with  no  good  results.  Strychnin  seemed  a  logical  remedy 
for  the  most  evident  symptoms,  and  was  tried  with  a  number  of  ani- 
mals with  varying  results.  Nine  head  of  cattle,  3  horses,  and  5  sheep 
were  treated  with  this  remedy.  Most  of  those  treated  were  in  bad 
condition,  and  it  was  a  fair  question  whether  in  any  of  these  cases 
unfavorable  results  should  not  have  been  expected,  or,  rather,  whether 
they  would  not  have  died  in  spite  of  all  treatment.  Two  of  the  cattle 
made  somewhat  remarkable  recoveries. 

Two  of  the  cattle  were  cured  during  the  strychnin  treatment  and 
there  seemed  no  good  reason  why  this  drug  should  not  have  the 
credit  of  the  cure,  but  it  was  true  that  other  animals  treated  with 
strychnin  died,  in  some  cases  partly,  at  least,  as  the  result  of  the 
poison.  None  of  the  horses  showed  improvement  from  the  use  of 
strychnin.  The  fact  that  several  of  the  animals  showed  indications 
of  poisoning  made  it  probabhe  that  strychnin  was  administered  in  too 
large  doses,  although  only  the  minimum  doses  of  the  ordinary  veteri- 
nary materia  medica  were  used.  It  seemed  probable  that  locoes 


TREATMENT   WITH   STRYCHNIN   IN   1906.  75 

perhaps  were  more  sensitive  to  the  effects  of  the  drug  and  should  be 
treated  in  especially  small  doses. 

Arsenious  acid  effected  a  cure  in  one  of  the  horses.  This  animal 
was  treated  at  the  agricultural  experiment  station  during  the  winter 
of  1906-7  under  the  general  direction  of  Doctor  Glover,  and  while  it 
was  a  clear  case  of  loco  in  the  fall  of  1906  with  all  the  typical  symp- 
toms, it  came  out  hi  the  spring  definitely  and  apparently  permanently 
cured.  This  animal  was  used  as  a  saddle  horse  during  the  summer  of 
1907  and  at  no  time  showed  any  of  the  signs  of  loco  poison,  if  we  except 
a  slight  loss  of  spirits. 

One  of  the  cattle,  too,  after  it  was  treated  with  Fowler's  solution, 
was  completely  cured. 

TREATMENT    WITH    STRYCHNIN    IN    1906. 

Case  4  was  a  steer  that  had  been  kept  in  the  loco-free  pasture  during 
the  season  of  1905.  In  1906  it  was  at  first  placed  in  the  loco-free 
pasture,  but  on  May  3  was  put  in  the  AragaUus  lamberti  pasture, 
where  it  commenced  to  eat  the  weed  and  continued  to  eat  it  with 
considerable  freedom.  Gradually  the  poison  began  to  show  its  effect, 
and  by  the  latter  part  of  August  the  animal  was  recognized  as  a  typical 
loco.  It  was  in  excellent  condition  at  the  beginning  of  the  season, 
when  turned  into  the  AragaUus  lamberti  pasture.  Plate  X,  figure  1, 
shows  its  condition  May  30,  1905;  figure  2,  taken  September  7,  1906, 
shows  its  condition  on  that  date,  when  it  was  very  distinctly  under  the 
influence  of  the  poison.  In  this  picture  the  attitude  is  that  of  the 
typical  loco.  It  had  lost  flesh  and  showed  nervous  symptoms  in  the 
way  of  responding  with  convulsive  movements  to  sudden  sounds,  and 
when  made  to  run  its  head  would  shake  with  the  palsied  movement 
which  is  characteristic  of  many  locoed  cattle.  In  figure  3  may  be 
seen  the  serous  sac  under  the  jaws,  one  of  the  typical  symptoms  of 
loco  poisoning  in  cattle.  The  steer  was  taken  up  on  September  '20 
for  treatment  and  was  given  daily  one-quarter  grain  of  strychnin 
hypodermically  until  September  30,  when  the  dose  was  increased  to 
one-half  grain.  During  this  time  it  did  not  gain  in  weight,  but  the 
nervous  phenomena  gradually  disappeared.  The  doses  were  kept  up 
until  October  6.  From  that  time  until  the  end  of  the.  season  it  was 
kept  in  the  loco-free  pasture.  When  it  was  sent  away  for  the  winter 
on  November  'JO  it  seemed  to  have  entirely  recovered  so  fur  as 
nervous  symptoms  were  concerned.  Figure  4  shows  the  animal's 
condition  August  22,  1907. 

The  curve  of  weight  for  1906  (text  fig.  15)  shows  that  this  steer 
did  not  make  normal  gains.  The  loss  for  the  end  of  October  and  for 
November,  however,  is  the  normal  result  for  that  time  of  the  year. 
Storms  and  shortness  of  food  caused  losses  that  year  in  all  the  ani- 


76 


THE  LOCO-WEED   DISEASE   OF   THE  PLAINS. 


mate  at  that  period.  In  the  spring  of  1907  the  animal  was  kept  in  the 
loco-free  pasture  about  one  week.  During  the  rest  of  the  summer  it 
was  kept  in  the  good  pasture  until  September  18.  From  this  time  until 
October  28  it  was  herded  on  loco.  As  the  curve  shows  (fig.  16),  it 
gained  during  this  time  about  300  pounds.  Plate  X,  figure  4, 
shows  that  on  August  22,  1907,  while  in  the  loco-free  pasture,  the 


FIG.  15.— Curve  of  weight  of  steer  No.  4,  1900. 

animal  was  in  fine  condition.  When  it  was  kept  on  loco,  however,  it 
ate  freely  and  at  the  close  of  the  season  it  again  showed  distinct  symp- 
toms of  loco  poisoning,  although  it  was  not  a  bad  case. 

Another  case,  No.  536,  was  a  Hereford  steer  belonging  to  Mr. 
Mattix,  of  Hugo,  which  was  brought  to  the  station  for  treatment  on 
July  9.  It  was  at  this  time  extremely  poor,  its  coat  was  rough,  its 


1200 
1150 
MOO 
1050 
1000 
950 


\9Q74PWl 


MAY 


juue 


V 


JULY 


OCr.    1907 


FIG.  16.— Curve  of  weight  of  steer  No.  4,  1907. 

eyes  staring,  and  it  stood  with  head  low  and  legs  spread  apart  because 
of  evident  weakness,  and  with  a  peculiar  curvature  of  the  fetlock 
joints  of  the  hind  feet  which  is  sometimes  noticed  in  locoed  animals. 
Plate  X,  figure  5,  shows  very  clearly  the  condition  of  the  animal  at 
this  time.  It  appeared  a  hopeless  case,  because  the  animal  not  only 
showed  the  effects  of  poison,  but  was  extremely  weak.  It  was  kept 
in  the  corrals,  as  it  was  too  weak  to  be  sent  out  into  the  pastures. 


BLL.  112,  BUREAU  OF  ANIMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  X. 


Case  4,  May  30,  1905.     Before  feeding  on  loco 
weed. 


Case  4,  September  7, 1905.     Showing  all  the  typ- 
ical symptoms  of  loco  poisoning. 


Case  4,  September  15, 1906.  Animal  under  influ- 
ence of  loco  and  with  a  noticeable  accumulation 
of  serous  fluid  under  chin. 


Case  4,  August  22,  1907.  Same  animal  as  in 
Figs.  1  to  3,  in  the  succeeding  year,  when  it 
no  longer  showed  symptoms  of  loco  poisoning. 


Case  536,  July  9, 190f>.  A  locoed itecr  with  curva- 
ture of  the  fetlock  joints,  which  is  peculiar  to 
some  locoed  animals. 


Case  536,  July  25,  1906.  The  same  animal  after 
treatment  with  itrychnine.  It  stands  in  nor- 
mal fashion  and  has  gained  much  in  strength 
and  in  weight. 


TREATMENT   WITH   STRYCHNIN   IN   1906.  77 

It  was  fed  upon  alfalfa  hay  and  some  grain,  and  was  given  hypo- 
dermically  one-half  grain  of  strychnin  daily.  The  strychnin  seemed 
to  take  effect  upon  it  almost  immediately  and  on  July  1 1  its  fetlock 
joints  had  straightened  out  and  the  animal  showed  itself  in  every 
way  very  much  improved.  The  doses  of  strychnin  were  kept  up 
from  July  9  until  July  21.  Most  of  this  time  the  action  of  the  bowels 
had  been  very  free,  but  as  at  this  time  it  seemed  somewhat  consti- 
pated, it  was  given  250  grams  of  Epsom  salts,  and  was  turned  into 
the  loco-free  pasture,  where  it  was  kept  until  July  30,  when  it  was 
brought  in  and  given  another  course  of  strychnin,  one-half  grain 
daily  until  August  6,  when  it  was  again  turned  into  the  loco-free 
pasture  and  was  considered  as  very  nearly  cured.  Plate  X,  figure  6, 
shows  its  improved  condition  on  July  25.  About  October  1  it  was 
turned  back  to  the  owner,  who  sent  it  out  upon  the  range  with  his 
other  cattle.  The  animal  was  seen  again  about  the  end  of  October 
and  it  was  evident  that  the  cure  was  complete  and  permanent.  Later 
in  the  season  the  steer  was  put  upon  the  market. 

Case  40  was  also  treated  with  strychnin.  This  was  a  large,  hand- 
some steer  which  was  received  in  the  spring  and  kept  in  the  loco-free 
pasture  until  July  18,  when  it  was  placed  in  the  Aragallus  lamberti 
pasture.  It  immediately  commenced  to  eat  the  loco,  and  from  this 
time  on  ate  it  with  rather  unusual  freedom,  seeming  to  prefer  it  to 
grass.  The  daily  notes  taken  by  the  observers  in  the  pasture  indicate 
that  it  ate  loco  rather  more  freely  than  any  of  the  other  cattle.  Its 
weight  was  1,235  pounds  when  put  in  the  Aragallus  lamberti  pasture. 
It  gradually  lost  weight,  and  on  October  16  weighed  1,160  pounds. 
Shortly  after  this  the  loco  symptoms  became  very  marked.  The 
peculiar  condition  of  the  hind  fetlock  joints  which  was  noticed  in  No. 
536  was  very  marked  in  this  animal  also.  At  the  end  of  October  the 
steer  was  taken  up  for  treatment.  At  this  time 'it  weighed  1,105 
pounds.  It  was  treated  hypodermically  with  one-half  grain  strychnin 
daily  and  fed  in  the  corrals  with  hay  and  chop.  This  treatment 
was  continued  until  November  5.  On  November  12  its  weight  was 
1,025  pounds.  It  was  taken  from  Hugo  to  Fort  Collins  to  continue 
treatment  through  the  winter.  From  December  9  until  December 
20  it  was  given  one-half  grain  of  strychnin  dully  and  showed  a  slight 
gain  in  weight.  The  treatment  was  then  discontinued  for  a  time, 
but  was  commenced  again  December  2S  and  continued  in  doses  every 
second  day  until  January  9.  On  January  31  it  weighed  1 ,210  pounds. 
Two  weeks  later  it  had  increased  to  1,300  pounds.  It  was  fed,  of 
course,  with  considerable  care,  and  on  February  23  was  sold  for  fat 
beef.  It  was  at  that  timo  in  fino  condition.  The  curve,  figure  17, 
shows  the  relation  of  the  changes  in  weight  to  the  feeding  of  loco  and 
treatment. 


78 


THE   LOCO-WEED    DISEASE    OF   THE   PLAINS. 


During  the  season  of  1906  none  of  the  horses  treated  with  strychnin 
showed  any  improvement,  and  the  same  can  be  said  of  the  sheep. 
It  mav  be  stated  that  the  doses  of  strychnin  in  the  case  of  both  horses 
and  cattle  were  either  one-quarter  or  one-half  a  grain,  and  in  the  case 
of  the  sheep  from  two-twentieths  to  eight-twentieths  of  a  grain. 

There  was  no  question  that  in  some  cases  there  were  symptoms  of 
strychnin  poisoning,  and  this  was  true  of  cattle,  horses,  and  sheep. 
It  seemed  probable  that  the  doses  of  strychnin  were  too  large,  so  that 
in  the  weakened  nervous  condition  of  the  animals  they  were  affected 
unfavorably.  It  appears  that  locoed  cattle  may  be  unusually  sus- 
ceptible to  the  influence  of  strychnin.  At  the  same  time  the  ex- 
tremely favorable  results  in  the  cases  of  Nos.  4,  536,  and  40  made  it 
seem  desirable  to  make  further  experiments  w4th  strychnin,  but  with 
the  use  of  much  smaller  doses. 


1250 

1150 
1100 

1906 

M4Y 

Jt//Vf 

JUIY 

/WGi/sr 

SffTfMffCff 

OCrOBCR 

HOVfMBffi 

ore  1906 

1907  J/IH. 

ffff   1907 

M^ 

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— 

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n^ 

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= 

1050 
1000 
950 

/ 

. 

'A7T/H 

7  4RA 

SJtll. 

'S  t*A 

fscffn 

n 

— 

—  ^ 

— 

£--. 

1        * 

FIG.  17. — Curve  of  weight  of  steer  No.  40. 
TREATMENT   WITH   ARSENIC   IN    1906. 

Arsenic  either  in  the  form  of  Fowler's  solution  or  of  arsenious  acid 
was  used  with  3  horses,  4  cattle,  and  4  sheep.  Two  of  the  horses 
died,  one  (No.  58),  a  mare,  was  cured.  The  history  of  this  case  is 
given  in  some  detail. 

The  mare  was  received  from  the  Fort  Collins  Agricultural  Experi- 
ment Station  on  May  18,  and  was  placed  in  the  loco-free  pasture. 
Her  weight  at  this  time  was  655  pounds.  She  had  been  an  old  saddle 
horse,  was  a  lively,  spirited  animal,  although  not  young,  and  in  June 
was  used  as  one  of  the  saddle  horses  at  the  station.  It  was  found, 
however,  that  her  nervous  disposition  made  her  somewhat •  unde- 
sirable for  general  work,  and  on  July  30  she  was  put  in  the  Aragallus 
lamberti  pasture  and  kept  there  until  October  9.  During  this  time 
there  is  no  evidence  that  she  ate  any  of  the  loco  weed.  Apparently 
she  devoted  herself  entirely  to  grass.  On  October  9  she  was  taken 
into  the  corral  and  fed  cut  Aragallus  lamberti  and  hay.  At  this  time 


TREATMENT   WITH   ARSENIC    IN    1906. 


79 


she  weighed  765  pounds.     She  was  kept  during  the  remainder  of  the 
season  upon  this  treatment. 

After  October  16  the  mare  gradually  lost  in  weight  and  on  Novem- 
ber 12  weighed  only  705  pounds.  At  this  time  she  was  weak  and  in 
her  peculiar  nervous  actions  showed  very  decided  loco  symptoms. 
She  would  start  at  sudden  noises  and  would  rear  when  any  sudden 
motion  was  made  near  by.  She  was  taken  to  Fort  Collins  for  treat- 
ment during  the  winter,  under  the  general  direction  of  Doctor  Glover. 
It  was  reported  from  there  on  December  14  that  she  was  very  badly 
locoed.  She  reared  when  excited,  and  could  not  be  led  or  tied.  This 
in  spite  of  the  fact  that  she  was  a  so-called  gentle  horse  and  had  been 
used  for  several  years.  On  December  1 6  treatment  was  commenced 
by  giving  her  2£  grains  of  arsenious  acid  in  chop.  This  treatment  was 
continued  until  January  8.  On  January  9  she  weighed  805  pounds, 
which  was  a  very  marked  gain,  as  on  December  12  she  weighed  only 
740.  On  March  1  she  weighed  865  pounds.  It  was  reported  at  this 


s 

1906   W 

JUNF 

Ml* 

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1906 

1907  J*#/ 

ffffy  1907 

850 
800 

tL  — 

750 
700 

z 

— 

=2 

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1 

1 

FIG.  18.— Curve  of  weight  of  horse  No.  58. 

time  that  the  man  in  charge  of  her  tried  to  ride  her,  but  could  not 
manage  her  well,  and  that  she  would  not  lead.  Her  legs  were  slightly 
swollen  on  this  date,  probably  from  an  overdose  of  arsenic.  No 
further  treatment  was  given  beyond  good  feed,  and  she  was  taken  to 
Hugo  in  the  middle  of  April  and  placed  in  the  loco-free  pasture.  For 
about  a  week  in  May  she  was  herded  upon  AragaUus  Itimberti  and  ate 
it  with  some  freedom.  She  was  then  put  back  in  the  loco-free  pasture, 
having  shown  no  symptoms  of  poisoning,  and  a  little  later,  May  10, 
was  a«rain  used  as  a  saddle  horse.  It  was  found  that  she  was  entirely 

O  ** 

reliable  and  showed  none  of  the  symptoms  of  loco  poisoning,  if  \ve 
except  a  slight  lack  of  spirit.  She  was  used  during  the  whole  summer 
in  the  general  work  of  the  station  as  a  saddle  horse  and  did  the  work 
well.  This  was  an  evident  case  of  cure  and  presumably  the  arsenic 
was  instrumental  in  effecting  it.  Unfortunately  we  have  no  good 
pictures  showing  the  progress  of  the  disease  and  cure  of  this  animal. 
The  curve  (fig.  IS)  shows  her  changes  in  weight  while  under  treatment. 
Of  the  horses  that  died  while  being  treated  with  arsenic,  one  was  a 
very  bad  case  and  probably  could  not  have  been  saved  by  any 


80 


THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 


method  of  treatment.  The  other  was  a  good  case  for  treatment,  but 
died  in  spite  of  all  that  was  done  for  her.  This  case  (No.  59)  became 
worse  very  rapidly,  there  being  only  eighteen  days  of  treatment  with 
Fowler's  solution  before  the  animal  died.  It  may  be  considered,  per- 
haps, as  a  case  of  rather  acute  poisoning. 

Of  the  sheep  treated  with  Fowler's  solution,  all  but  one  died,  and 
we  did  not  feel  at  all  certain  that  the  cure  of  this  one  was  due  more  to 
the  Fowler's  solution  than  to  the  effect  of  good  food. 

Of  the  cattle  treated  with  Fowler's  solution,  all  but  one  died.  The 
one  cured  (No.  28)  was  an  old  milch  cow  which  was  received  from 
Denver  and  at  first  placed  in  the  loco-free  pasture.  She  was  kept 
there  until  June  18,  when  she  was  brought  into  the  corrals  and  fed 
on  Astragalus  mollissimus.  At  that  time  she  was  heavy  with  calf, 
and  inasmuch  as  the  loco  weeds  are  popularly  supposed  to  produce 

abortion,  it  was  de- 
sired to  feed  this 
animal  loco  to  see 
whether  any  effect 
would  be  produced 
on  the  birth  of  the 
calf.  She  was  fed 
in  the  corral  from 
June  18  until  July 
22,  with  the  excep- 
tion of  occasional 
days  in  the  loco 
pasture,  her  rations 
consisting  of  fresh- 
cut  Astragalus  mol- 
lissimus and  hay. 

She  ate  both  with  very  great  freedom  and  showed  a  strong  appe- 
tite for  the  loco  weed.  By  the  end  of  July  it  was  necessary  to 
terminate  the  experiment  with  the  Astragalus  mollissimus  because 
it  was  found  impossible  to  obtain  enough  for  feeding  purposes, 
and  on  August  2  we  commenced  feeding  her  hay  and  fresh-cut 
Aragallus  lamberti.  It  was  noted  on  August  7  that  she  showed 
no  effects  from  the  loco  feeding,  but  on  the  14th  the  effects  began 
to  appear.  She  dropped  her  calf  on  August  20.  Her  calf  was 
small  and  weak,  but  was  fully  matured.  Whether  its  weakness 
could  be  considered  as  the  effect  of  the  loco  is  a  matter  of  doubt. 
The  cow  was  kept  in  the  corral  and  fed  Aragallus  lamberti  and 
hay  until  September  17.  During  this  time  the  effect  of  the  loco 
poison  became  more  and  more  evident.  Figure  19  shows  the  con- 
dition of  the  animal  on  August  27.  At  this1  time  the  serous  sac 
under  the  jaw,  typical  of  many  locoed  animals,  was  very  promi- 
nent. She  was  put  in  the  loco-free  pasture  on  September  18  and 


FIG.  19.— Case  28,  August  27,  190ti.    Cow  after  it  has  become  locoed,  but 
not  a  bad  case.    The  serous  sac  under  the  chin  is  very  prominent. 


RESULTS   OF   TREATMENT  IN   1906. 


81 


kept  there  with  no  further  treatment  until  October  31,  in  order  to 
see  whether  simply  having  good  feed  and  being  taken  away  from 
the  loco  might  not  bring  about  her  recovery.  During  this  time  she 
had  gained  slightly  in  weight  at  first  and  then  lost.  On  November  3 
we  commenced  treating  her  with  15  c.  c.  of  Fowler's  solution  daily. 
This  treatment  was  continued  until  the  end  of  the  month,  when  she 
was  taken  to  Fort  Collins  for  further  treatment  during  the  winter. 
During  the  latter  part  of  December  she  was  treated  with  potassium 
iodid,  but  with  no  particularly  good  effect.  On  February  1  treat- 
ment with  Fowler's  solution  was  resumed  and  she  received  15  c.  c. 
daily  through  the  month.  Later  the  treatment  was  discontinued. 
About  the  middle  of  March  she  was  shedding  her  winter  coat  and 
getting  fat,  and  the  last  of  March  she  was  fat  enough  for  beef. 

This  was  evidently  a  cure,  and  the  credit  of  the  cure  must  be 
given  to  Fowler's  solution.  The  after  history  of  No.  28  is  inter- 
esting, as  she  was  kept  during  the  summer  of  1907  upon  a  pasture 


§ 

1906 

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FIG.  20.— Curve  of  weight  of  cow  No.  28,  1906. 

where  loco  was  very  abundant  and  ate  more  or  less  of  it  through 
the  season,  but  without  any  noticeably  deleterious  effects.  The 
curves  (figs.  20  and  21)  show  the  changes  in  weight  in  the  two 
seasons  in  their  relation  to  the  treatment. 

RESULTS  OF  TREATMENT  IN*  1906. 

In  summing  up  the  general  results  of  the  reined  in  1  measures 
attempted  in  1906,  it  seemed  quite  clear  that  of  all  the  remedies 
with  which  experiments  were  made  success  had  been  reached  with 
only  two — strychnin  and  Fowler's  solution.  The  marked  cases  of 
euro  in  cattle  with  strychnin  seemed  to  make  it  very  probable  that 
this  remedy  would  prove  useful.  It  also  was  evident  from  the 
deaths  which  occurred  from  the  use  of  strychnin  that  it  would  be 
necessary  to  use  very  much  smaller  doses. 

The    results    from    Fowler's    solution    were    somewhat    doubtful. 
We  have  the  cases  of  horse  No.  58  and  of  cow  No.  28,  which  presuma- 
bly were  aided  in  their  recovery  by  the  use  of  the  solution. 
79154— Bull.  112—09 6 


82 


THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 


Simply  a  statement  of  the  number  of  cases  in  which  there  was  a 
cure  or  a  failure  to  cure  would  hardly  give  a  fair  idea  of  the  results 
of  these  experiments,  but  in  each  case  the  individual  peculiarities 
of  the  patient  should  be  considered.  As  a  matter  of  fact,  in  most  of 
the  cases  which  were  subjected  to  treatment  in  1906  the  disease  was 
very  far  advanced,  so  that  the  chances  of  cure  with  any  course  of 
treatment  were  very  small.  This  was  true  in  nearly  all  the  cases 
of  sheep  and  in  most  of  the  horses  and  cattle.  The  recoveries  came 
only  after  a  somewhat  prolonged  course  of  treatment.  One  of  the 
cattle  which  recovered  was  treated  forty  days,  another  twenty- 
seven  days.  A  horse  which  recovered  on  a  treatment  of  arsenious 
acid  was  treated  for  thirty  days.  From  the  summer's  work  it 
seemed  wise  to  experiment  further  with  strychnin  and  arsenic, 


J 

1100 
1050 
1000 
950 
900 

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MORE  Off  i£Si. 

itt/S  LA/WBi 

252 

FIG.  21.— Curve  of  weight  of  cow  No.  28, 1907. 

using  the  former  mainly  with  cattle  and  the  latter  for  the  most 
part  with  horses. 

During  the  summer  of  1907,  then,  it  was  determined  to  make  as 
fair  a  trial  as  possible  of  strychnin  and  arsenic,  using  smaller  doses 
of  the  strychnin.  Inasmuch  as  some  success  had  been  obtained  with 
arsenious  acid  and  Fowler's  solution,  experiments  were  made  with 
atoxyl  and  sodium  cacodylate,  it  being  thought  that  other  forms 
of  arsenic  might  have  the  same  good  effects.  It  may  be  remarked 
that  the  pathological  lesions  of  locoed  animals  are  surprisingly  like 
those  produced  by  the  trypanosomes,  and,  granted  that  the  use  of 
atoxyl  in  trypanosomiasis  succeeds  not  only  because  of  its  specific 
effects  on  the  parasites  but  also  because  of  its  effect  on  the  system 
generally,  it  might  be  possible  that  in  atoxyl  there  would  be  a  remedy 
also  for  the  condition  found  in  locoes.  Sodium  cacodylate  was  used 
because  of  the  marked  benefits  sometimes  produced  in  cases  of  ane- 
mia in  human  patients. 


EXPERIMENTS    WITH   REMEDIES,   1907.  83 

TREATMENT    OF   CATTLE    IX    1907. 

Fowltr's  solution. — Only  one  of  the  cattle  (No.  565)  was  treated 
with  Fowler's  solution.  It  was  a  typical  loco,  although  not  extremely 
poor,  and  the  nervous  symptoms  were  not  as  pronounced  as  in  some 
cases.  The  solution  was  given  in  15  c.  c.  doses  and  was  continued  for 
fifty-three  days.  The  steer  gained,  but  quite  slowly.  Its  weight  at 
the  beginning  of  treatment  was  580  pounds,  and  when  it  was  dis- 
charged it  weighed  670  pounds.  It  was  considered  a  cure,  but  the 
results  of  Fowler's  solution  did  not  seem  to  be  as  marked  as  those 
that  were  obtained  with  strychnin. 

Atoxyl. — Atoxyl  was  used  in  three  cases — Nos.  42,  546,  and  558. 
No.  42  was  one  of  the  station  animals  that  had  eaten  loco  during  a 
considerable  portion  of  the  preceding  season,  but  did  not  show  marked 
symptoms  of  loco  poisoning.  This  steer  was  herded  upon  loco  from 
the  beginning  of  the  season  in  1907  until  the  1st  of  August.  As  early 
as  July  4  it  was  noted  that  the  animal  was  holding  its  head  low  in  the 
typical  loco  fashion  and  that  the  movements  of  its  legs  were  somewhat 
nervous  and  jerky.  A  few  days  later  the  steer  had  the  staring  look 
in  the  eyes  which  is  seen  in  so  many  locoes  and  the  bending  of  the 
fetlock  joints  of  the  hind  legs.  It  was  kept,  however,  on  the  loco 
until  August  1,  when  it  was  taken  in  for  treatment.  At  that  time 
the  loco  symptoms  were  very  pronounced  and  the  animal  was  quite 
weak.  It  was  given  0.28  gram  atoxyl  and  this  amount  was  increased 
in  succeeding  days  until  a  maximum  of  1.4  grams  was  reached.  This 
was  given  until  September  2.  When  the  treatment  commenced,  on 
August  2,  the  steer  weighed  840  pounds.  At  the  conclusion  of  the 
course  of  treatment  the  weight  was  888  pounds.  From  that  time  the 
animal  was  kept  in  the  loco-free  pasture  and  gradually  increased  in 
weight  until  the  end  of  October,  when  it  weighed  960  pounds.  Before 
treatment  it  had  the  typical  dejected  attitude  of  the  loco  and  (lie 
peculiar  flexing  of  the  fetlock  joints  of  the  hind  legs,  but  recovered  so 
that  it  was  bright  and  walked  in  normal  fashion.  This  case  can  be 
considered  as  a  cure,  and  the  credit  of  the  cure  probably  can  be  given 
to  atoxyl.  The  curves  (figs.  22  and  2.3)  show  the  changes  in  weight  in 
the  history  of  the  animal. 

No.  546  was  treated  for  a  time  with  atoxyl  and  afterwards  with 
strychnin,  as  there  seemed  to  be  no  gain  from  the  atoxyl.  The  gain 
under  strychnin  in  this  case  was  slight. 

The  third  case  which  was  treated  with  atoxyl  (No.  558)  was  a  bad 
case  from  the  start,  and  probably  no  remedy  would  have  succeeded 
in  bringing  the  animal  out. 

Sodium  cacodylate. — Five  of  the  cattle  were  treated  with  sodium 
cacodylate,  and  4  of  these  (Nos.  3,  6,  35,  and  548)  were  cured.  The 
one  not  cured  (No.  559)  was  in  the  last  stages  of  the  disease  and 
probably  beyond  any  cure. 


84 


THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 


No.  35  was  a  cow  belonging  to  the  experiment  station  which  had 
been  eating  AragaUus  lambcrti  during  the  season  of  1906,  but  did  not 
seem  to  be  affected  by  the  poison.  During  1907  she  was  herded  upon 
loco  from  the  first  of  the  season  and  ate  the  weed  quite  freely.  On 
July  1  she  was  taken  in  for  treatment,  as  at  this  time  she  showed  verv 


I 

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FIG.  22.— Curve  of  weight  of  steer  No.  42,  1900. 


distinct  signs  of  being  locoed.  For  a  considerable  time  before  this 
she  had  been  constantly  losing  weight.  She  was  given  0.6  gram  of 
sodium  cacodylate  hypodermically.  This  treatment  was  continued 
from  July  1  to  August  10.  Her  weight  just  before  the  treatment 
commenced  was  792£  pounds.  At  the  time  the  treatment  ceased  she 


I 

950 


900 
850 
600 


1907 JPfVL 


MJY 


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OCr    1907 


FIG.  23.— Curve  of  weight  of  steer  No.  42,  1907. 

weighed  882 £  pounds.  From  this  time  she  was  kept  in  the  loco-free 
pasture  and  at  the  end  of  October  weighed  990  pounds  (see  fig.  24). 
No.  548  was  a  heifer  belonging  to  Mr.  Woods,  of  Hugo.  She  was 
brought  to  the  station  from  the  Woods  ranch  on  April  22.  She  was 
very  thin  and  wild  eyed  and  when  eating  showed  in  a  marked  way 
the  peculiar  stiff  action  of  the  jaws  which  is  frequently  characteristic 


TREATMENT   OF   CATTLE   IN    1907. 


85 


of  locoed  animals.  She  was  given  a  few  doses  of  magnesium  sulphate 
and  three-twentieths  of  a  gram  of  strychnin  was  administered  hypo- 
dermically  from  April  23  to  April  27.  From  this  date  sodium  cacody- 
late  was  given  hypodermically  in  0.3-gram  doses,  and  the  treatment 
was  continued  until  May  13.  The  dose  was  increased  to  0.4  gram 


1000 

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FIG.  24. — Curve  of  weight  of  cow  No.  35. 


from  May  14  until  May  31.  From  June  1  until  June  15  daily  doses  of 
three-twentieths  grain  strychnin  were  given.  On  June  16  she  was 
put  in  the  loco-free  pasture  and  the  treatment  was  stopped.  Her 
weight  at  the  beginning  of  the  season  was  440  pounds.  At  the  time 
treatment  was  discontinued  she  weighed  530  pounds  and  gained 


1 

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600 
550 
500 
450 

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Kio.  '£>.    Curve  of  weight  of  lifift-r  No.  64H. 

continually  from  that  time  on  (see  text  fig.  -5).  She  was  kept  in 
the  loco-free  pasture  until  the  middle  of  September,  when  she 
weighed  702  J  pounds.  The  gain  of  this  animal  was  very  marked  and 
the  change  from  a  poor,  worthless  animal  in  the  spring  into  an  animal 
fit  for  beef  in  midsummer  was  very  noticeable. 

No.  5")ti  was  a  steer  received  from  Mr.  Moshei,  of  Hugo.     It  was 
one  of  the  wild  locoes  and  very  difficult  to  drive.      It  was  extremely 


86  THE   LOCO-WEED   DISEASE   OF   THE  PLAINS. 

excitable  when  first  brought  to  the  station.  Its  coat  was  rough  and 
the  animal  was  quite  thin.  We  commenced  by  giving  this  animal 
three-twentieths  grain  strychnin  doses,  but  this  was  continued  for 
only  four  days,  after  which  it  was  treated  with  one-half  gram  sodium 
cacodylate,  given  hypodermically.  This  treatment  was  continued 
from  July  14  to  August  23.  When  treatment  commenced,  the  steer 
weighed  717^  pounds.  At  the  time  treatment  was  discontinued  its 
weight  was  810  pounds.  It  was  kept  until  the  middle  of  October,  at 
which  time  it  weighed  925  pounds. 

Strychnin. — Fourteen  head  of  cattle  in  1907  were  treated  with 
strychnin.  Of  these,  Nos.  503,  559,  561,  and  566  died.  No.  559, 
when  received,  was  very  poor  and  weak,  and  lived  a  comparatively 
short  time.  No.  566  was  so  weak  that  a  few  days  after  it  was  received 
it  fell  near  a  creek  with  its  nose  under  water  and  was  drowned.  No. 
561  had  a  complication  of  troubles  that  led  to  its  death,  although  the 
treatment  with  strychnin  was  evidently  beneficial.  It  gained  in 
weight  and  apparently  was  doing  better,  but  died,  as  the  autopsy 
showed,  of  pericarditis. 

Nine  of  the  animals  treated  were  distinct  cures.  Of  these,  No.  38 
had  been  kept  in  the  loco  pasture  during  the  months  of  October  and 
November  in  1906,  but  without  showing  any  effect  of  loco  poisoning. 
In  1907  it  was  herded  on  AragaUus  lamberti  from  the  beginning  of  the 
season  until  July  1,  when  it  was  taken  in  for  treatment.  For  some 
little  time  before  this  it  had  been  showing  distinct  loco  symptoms, 
carrying  its  head  low,  and  being  slow  in  its  movements.  It  showed 
more  or  less  lack  of  muscular  coordination  in  its  limbs.  A  few  days 
before  this,  on  June  27,  it  had  broken  a  horn  and  it  became  necessary 
to  cut  it  off.  It  lost  considerable  blood  in  this  operation,  and  this  may 
have  somewhat  increased  its  inactivity.  It  was  given  four-twentieths 
grain  of  strychnin  for  five  days,  when  the  dose  was  reduced  to  three- 
twentieths  grain.  This  was  continued  until  July  31.  During  this 
time  it  became  extremely  weak — so  weak  that  it  could  not  be  driven 
to  the  stock  yards  for  weighing,  or  even  taken  out  into  the  good  pas- 
ture, but  was  kept  near  the  house  in  the  horse  pasture.  It  began  to 
pick  up  in  about  a  couple  of  weeks,  and  on  July  24  was  taken  out  into 
the  loco-free  pasture  with  the  other  animals.  Its  weight  on  July  26 
was  700  pounds.  From  July  31  it  was  given  four-twentieths  grain 
of  strychnin  daily,  and  this  was  continued  until  August  23,  when  it 
weighed  760  pounds.  It  was  kept  in  the  loco-free  pasture  during 
the  remainder  of  the  season  and  on  November  1  weighed  875  pounds. 
It  was  then  considered  as  entirely  cured.  The  curve  of  weight  is 
shown  in  text  figure  26. 

No.  547  was  a  heifer  received  from  Mr.  Woods,  of  Hugo.  It  was 
brought  to  the  station  April  22.  It  was  a  yearling  heifer,  very  thin 
and  wild  eyed,  and  dragged  its  hind  legs  when  walking,  in  the  typical 


TREATMENT   OF   CATTLE   IN   1907. 


87 


loco  fashion,  and  it  was  noticed  that  it  ate  with  the  stiff  motion  of  the 
jaws  which  is  peculiar  to  locoes.  The  animal  was  treated  by  admin- 
istering three-twentieths  grain  strychnin  hypodermically  daily  until 
May  14,  when  the  dose  was  increased  to  four-twentieths  grain.  This 
treatment  was  continued  until  May  25.  Besides  the  treatment  with 


850 
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750 
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9 

FIG.  26.— Curve  of  weight  of  steer  No.  38. 


strychnin  the  heifer  was  given  several  doses  of  Epsom  salts  in  order 
to  insure  free  movement  of  the  bowels.  From  April  25  she  was  kept 
in  the  loco-free  pasture  until  the  latter  part  of  the  season.  When 
received,  she  weighed  465  pounds;  on  May  24,  when  treatment  was 


§ 

1907, 

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FIG.  27. — ('iin-e  of  weight  of  heifer  No.  547. 

discontinued, her  weight  was  510  pounds,  and  it  continued  to  increase 
until  the  middle  of  vSeptemlx'r,  when  she  weighed  712J  pounds. 

Plate  XI,  figures  1  and  2,  show  the  animal's  condition  on  April  23 
and  August  22.  On  June  4  the  heifer  was  practically  a  cured  animal 
and  was  in  thoroughly  good  shape,  while  at  the  date  of  the  last  pic- 
ture, August  22,  she  was  in  condition  fit  for  market.  The  curve  (fig. 
27)  shows  the  increase  in  weight. 


88 


THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 


No.  555  was  a  steer  received  from  Mr.  Mosher,  of  Hugo,  on  July  9. 
It  was  weak,  with  rough  coat,  in  poor  flesh,  and  quite  wild.  Treatment 
was  commenced  on  July  10  with  three-twentieths  of  a  grain  strychnin 
daily  and  continued  until  August  23.  During  this  time  it  had  gained 
60  pounds.  Subsequently  it  was  kept  in  the  loco-free  pasture  until  it 
was  returned  to  the  owner  about  the  middle  of  October.  At  that 
time  it  weighed  750  pounds  and  was  considered  a  complete  cure. 
The  curve  (fig.  28)  shows  its  increase  in  weight. 

Two  other  cattle  were  treated  with  strychnin.  One  of  them,  No. 
68,  was  treated  for  too  short  a  time  to  show  any  marked  effects, 
although  it  was  noticed  that  there  was  some  improvement.  The  other 
one,  No.  569,  showed  improvement,  but  had  other  troubles  which 
prevented  a  complete  cure. 


1 

750 


700 
650 
600 


1907  J(/iY 


AUGUST 


OCT.    1907 


FIG.  28.— Curve  of  weight  of  steer  No.  555. 
TREATMENT   OF    HORSES    IN    1907. 

During  the  season  of  1907  seven  horses  and  one  mule  were  treated. 
Strychnin  was  used  in  only  one  case,  and  in  this  case  not  only  the 
strychnin  was  used,  but  also  sodium  cacodylate.  It  is  difficult  to  tell 
just  what  the  effect  of  either  of  these  substances  was  upon  the  horse 
treated  (No.  22).  It  gained  during  the  season,  but  gained  somewhat 
slowly  and  could  not  be  considered  as  a  cure.0 

The  other  seven  animals  were  treated  with  Fowler's  solution  alone. 
Of  these,  two  were  distinct  cures,  and  the  others  with  one  exception 
all  made  gains.  The  exception  was  the  mule.  This  was  an  old 

QNo.  22  was  pastured  during  the  season  of  1908  with  no  further  treatment  and 
became  a  healthy,  handsome  animal. 


BUL.  112.  BUREAU  OF  ANIMAL  INDUSTRY,  U.  S.  DEPT.  OF  AGRICULTURE. 


PLATE  XI. 


Case  547,  April  23, 1907.    A  heifer  in  an  advanced 
stage  of  loco  poisoning. 


Case  547,  August  22, 1907.  Completely  recovered 
under  treatment.  Heifer  was  sold  for  fat 
beef. 


Case  551,  June  14,  1907.     A  horse  in  advanced 
stages  of  loco  poisoning;  weight  510  pounds. 


Case  551,  September  20,  1907.     After  course  of 
treatment ;  weight  825  pounds. 


Case  71,  June  10, 1907.     A  locoed  sheep,  emaciated 
and  extremely  nervoui. 


Case  71,  September  22,  1907.     Recovered,  as  a 
result  of  course  of  treatment. 


TREATMENT   OF    HORSES   IN    1907. 


89 


animal,  a  chronic  loco,  and  its  death  was  due  not  only  to  the  effect  of 
the  loco  poisoning,  but  doubtless  to  old  age.  The  history  of  two  of 
the  animals  treated  is  of  special  interest  and  is  given  below. 

No.  551,  belonging  to  Mr.  Mosher,  of  Hugo,  was  received  May  21. 
It  had  been  locoed  the  previous  season  and  had  been  fed  on  grain  all 
through  the  winter.  Plate  XI,  figure  3,  shows  its  general  appearance 
on  June  14.  It  was  a  miserable  animal — was  very  poor,  its  winter  coat 
was  still  on  in  spots,  and  gave  it  an  especially  woe-begone  appearance. 
It  stood  about  in  a  listless  way,  with  its  head  down,  but  when  dis- 
turbed, as  by  a  sudden  noise,  it  would  jump  and  rear  up,  showing  the 
unstrung  condition  of  its  nervous  system.  It  was  4  years  old  and 
weighed  525  pounds.  The  case  seemed  almost  hopeless  and  hardly 
worth  experimenting  with.  It  was  put  on  daily  doses  of  Fowler's  solu- 


800 
750 
700 
650 
600 
550 


1907  M/lY 


JL/A/f 


JULY 


OCr.    1907 


FlQ.  29.— Curve  of  weight  of  horse  No.  531. 

tion  and  given  some  chop  and  oil  meal  daily  in  addition  to  its  pasture 
feed.  It  gained  rapidly.  Figure  4,  Plate  XI,  shows  its  appearance 
on  September  20.  The  treatment  was  continued  thirty-three  days, 
but  the  animal  was  kept  in  the  pasture  through  most  of  the  season. 
In  the  fall  it  weighed  810  pounds  and  was  a  fine,  sleek-looking 
horse.  The  curve  (fig.  29)  shows  its  increase  in  weight  as  the  result 
of  treatment. 

No.  504  was  a  gelding  belonging  to  Mr.  Norlhnip,  of  Hugo.  Tie 
was  7  years  old,  had  boon  used  as  a  work  horse,  and  had  boon  consid- 
ered a  gentle  and  valuable  animal.  Within  two  works  preceding  the 
timo  that  he  was  brought  to  the  station  he  had  developed  peculiar 
nervous  symptoms — would  throw  himself,  kick,  and  bohavo  in  a  very 
erratic  manner  generally,  so  that  it  was  considered  unsafe  to  use  him 
longer  as  a  work  horse.  He  was  put  on  daily  doses  of  Fowler's  solu- 


90  THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 

tion  and  fed  a  little  chop  each  day.  The  treatment  was  continued 
for  twenty-eight  days,  when  he  was  taken  by  the  owner  and  again 
put  tq  work.  He  gave  no  further  trouble  and  was  later  sold  as  a 
sound  horse. 

Of  the  others,  No.  572  was  treated  for  so  short  a  time  that  it  was 
impossible  to  say  whether  very  much  benefit  was  received  from  the 
treatment.  It  was  a  horse  belonging  to  Mr.  Dayton,  was  at  the 
ranch  only  ten  days,  and  it  was  difficult  to  say  when  it  was  discharged 
whether  it  had  really  made  very  much  gain  or  not. 

One  horse  was  treated  at  Woodland  Park.  This  animal  was  con- 
fined in  a  corral  and  fed  chiefly  upon  old  hay.  Fowler's  solution  was 
administered  in  its  drinking  water.  The  horse  was  not  under  constant 
observation,  as  were  the  animals  in  Hugo,  but  it  made  steady  gain 
under  the  treatment. 

TREATMENT    OF    SHEEP   IN    1907. 

One  sheep  was  treated  in  1907.  This  was  brought  by  Mr.  Frank 
Hamp,  and  while  the  history  of  its  feeding  previous  to  the  time  when 
it  was  brought  to  the  station  was  not  known,  it  was  pronounced  by 
Mr.  Hamp,  an  experienced  sheepman,  as  a  good  case  of  loco  poisoning. 
It  was  received  June  10.  It  was  in  fair  flesh,  but  in  a  highly  nervous 
state.  Its  head  was  held  high  and  shook  with  a  peculiar  vertical  motion 
so  that  its  teeth  rattled  together.  It  certainly  deserved  the  name  of 
crazy.  It  was  put  on  one-twentieth  grain  doses  of  strychnin  and 
showed  marked  improvement  in  less  than  two  weeks.  The  treat- 
ment was  continued  for  thirty-three  days,  when  the  nervous  symp- 
toms had  disappeared,  and  it  appeared  all  right  in  every  way.  This 
animal  seemed  to  be  a  perfect  cure.  Plate  XI,  figures  5  and  6,  show 
its  condition  when  received,  June  10,  and  when  it  was  considered  a 
cure,  September  22. 

A  number  of  sheep  that  were  left  at  the  station  by  Mr.  Mclntyre 
and  were  considered  locoes  were  kept  during  the  season,  but  it  was 
decided  that  none  of  them  were  cases  of  loco.  They  showed  no  tend- 
ency to  eat  the  plant,  would  eat  grass  simply,  and  it  was  decided  that 
the  poor  condition  of  the  animals  when  received  was  largely  the  result 
of  the  presence  of  animal  parasites.  Some  of  them  were  treated  for 
(Estrus  ovis,  and  all  came  out  in  the  fall  in  good  condition  without 
any  further  treatment. 


PART  III.— RESULTS  AND  CONCLUSIONS. 
CAUSE  OF  THE  DISEASE. 

The  first  and  most  important  question  arising  was  to  decide 
whether  the  disease  was  caused  by  the  loco  plants.  While  the  results 
of  previous  investigation  cast  much  doubt  on  their  poisonous  charac- 
ter, the  great  majority  of  the  stockmen  were  agreed  that  the  loco 
plants  were  at  the  bottom  of  the  trouble.  Great  interest,  therefore, 
was  attached  to  the  feeding  experiments.  At  first  it  appeared  that  it 
would  be  shown  that  they  were  harmless.  The  animals  placed  in  the 
loco  pasture  not  only  did  not  suffer  from  any  harmful  effects  of  the 
weed,  but,  on  the  other  hand,  grew  sleek  and  fat.  The  horses  fed  in 
the  corrals  showed  no  unusual  symptoms.  This  went  on  for  some 
weeks.  When  the  effects  of  the  poison  began  to  show  themselves 
they  came  very  suddenly,  and  within  a  short  time  the  animals  suc- 
cumbed entirely.  The  conditions  in  the  feeding  experiments  were 
such  that  the  deaths  of  these  animals  must  have  been  caused  by  loco. 
As  compared  with  animals  under  conditions  in  other  respects  iden- 
tical, the  loco  eaters  invariably  grew  poor  and  eventually  died.  In 
the  cases  where  loco  was  fed  exclusively  it  may  of  course  be  said 
that  the  trouble  was  a  lack  of  nutrition  in  the  plant.  This  possibly 
might  have  been  the  case  in  some  of  the  horses  of  the  first  season,  but 
in  the  other  cases  an  abundance  of  other  feed  was  provided  and  in 
spite  of  that  the  animals  went  down. 

During  the  second  season  a  careful  record  of  weights  was  kept  and 
curves  made  to  show  the  changes  during  the  season.  The  curves 
show  in  a  striking  way  the  fact  that  loss  of  weight  always  followed 
the  feeding  of  loco.  All  the  horses,  cattle,  and  sheep  that  ate  loco 
in  any  amount  were  affected.  No.  10  was  especially  interesting, 
because,  although  he  ate  loco,  he  did  it  in  moderation,  so  that  he 
lived  in  a  comparatively  fair  condition,  but  with  less  than  the  normal 
increment  in  weight. 

During  the  third  season,  too,  the  curves  of  weight  showed  some 
loss  whenever  any  considerable  amount  of  loco  was  eaten.  In  the 
summer  of  1907  there  was  no  forced  feeding  of  loco,  but  the  animals 
experimented  upon  were  kept  constantly  where  loco  was  abundant, 
and  a  daily  record  was  kept  of  what  was  oaten  by  the  animals  when 
they  were  in  the  field.  It  was  noticed  that  the  weights  varied 
much,  according  to  the  amount  of  loco  eaten.  No.  10  kept  on  in  the 


92  THE   LOCO- WEED   DISEASE   OF   THE   PLAINS. 

third  summer  as  he  had  before,  with  the  same  general  result,  being 
a  rather  poor  specimen  of  a  steer,  but  not  suffering  largely  from  his 
bad  habit. 

Of  the  previously  suggested  causes  of  the  disease  other  than  the 
plants  themselves,  most  had  no  reasonable  basis  and  no  discussion 
of  them  is  necessary.  The  theory  of  animal  parasites,  however, 
did  have  a  definite  experimental  basis.  It  was  noticed  in  the  begin- 
ning of  our  work  on  horses  and  cattle  that  not  only  was  there  no 
unusual  number  of  parasites  present  in  the  subjects,  but  in  many 
cases  the  number  was  unexpectedly  small.  The  horses  had  bots, 
as  .do  nearly  all  horses,  but  the  number  of  intestinal  worms  was 
remarkably  small.  In  many  of  the  cattle  no  parasites  at  all  were 
discovered.  Examination  of  the  blood  gave  no  evidence  of  blood 
parasites. 

With  the  sheep,  however,  it  was  a  different  matter.  The  general 
presence  of  (Estrus  ovis  and  Thysanosoma  actinioides  was  very  notice- 
able. Inasmuch  as  the  symptoms  produced  by  (Estrus  ovis  some- 
times resemble  closely  those  of  loco,  a  skeptical  person  might  well 
question  the  fact  of  loco  poisoning.  Sheep,  too,  are  erratic  about 
their  feeding,  and  in  many  cases  it  is  a  matter  of  some  difficulty  to 
get  exact  evidence  of  any  considerable  feeding  upon  the  weed.  If 
we  not  had  our  experience  with  horses  and  cattle  before  experiment- 
ing with  sheep,  it  is  very  likely  that  we  should  have  considered 
Marshall's  conclusions  as  confirmed  by  our  observations.  But  having 
already  acquired  positive  evidence  in  regard  to  other  animals,  we 
were  not  as  likely  to  be  skeptical  in  regard  to  sheep.  After  some 
experience  we  could,  by  post-mortem  examination,  distinguish  locoes 
readily,  but  it  is  very  difficult  before  death  to  tell  a  locoed  sheep  from 
one  suffering  from  grub  in  the  head. 

SYMPTOMS  OF  LOCO  POISONING. 

The  field  work  has  added  very  little  new  material  to  what  had 
already  been  published  in  regard  to  the  symptoms  of  loco  disease.  It 
appears  that  in  some  cases  authors  had  exaggerated  these  symptoms 
and  many  of  the  recorded  symptoms  can  not  be  verified,  but  in  gen- 
eral they  were  correct. 

During  the  early  period  of  loco  feeding  there  are  no  symptoms  of 
poisoning.  Horses  and  cattle  will  eat  quite  freely  of  the  weed  for  a 
considerable  period  with  no  apparent  ill  effects  and  may  even  gain 
considerably  in  flesh. 

The  first  symptoms  of  loco  poisoning  in  hor33s  are  in  the  gait. 
The  animal  walks  with  a  peculiarly  stiff  motion.  It  staggers  as  it 
walks,  frequently  moving  the  hind  limbs  with  a  noticeable  drag,  as 
though  they  were  partially  paralyzed.  Its  hind  legs  may  be  kept 


SYMPTOMS   OF   LOCO   POISONING.  93 

far  apart,  as  if  in  an  attempt  to  support  itself.  In  stepping  over  an 
obstacle  it  lifts  its  feet  unusually  high  with  a  jerking  motion,  and  may 
leap  unnecessarily  high,  as  though  unable  to  judge  of  distance.  It 
may  stumble  and  fall,  getting  up  with  a  good  deal  of  difficulty.  The 
animal  develops  a  solitary  habit,  staying  away  from  the  rest  of  the 
bunch.  This  solitary  habit  is  supposed  by  some  to  be  due  to  its  desire 
to  hunt  loco,  but  is  probably  simply  because  of  its  general  nervous 
depression.  These  symptoms  may  appear  when  the  animal  is  in 
fairly  good  flesh.  It  becomes  slow  and  "dopy."  It  may  stand  for 
hours  without  eating  and  not  go  to  water  for  days.  When  it  attempts 
to  drink  it  may  have  difficulty  in  getting  its  head  to  the  water,  and, 
when  it  reaches  it,  may  move  its  mouth  as  though  attempting  to  eat 
rather  than  with  the  motions  of  drinking.  This  peculiarity  in  drink- 
ing is  accompanied  by  equally  peculiar  motions  in  eating  and  may 
be  very  pronounced  before  the  animal  deteriorates  much  in  flesh,  as 
shown  in  Plate  V,  figure  1. 

The  animal  may  eat  little  but  loco,  going  from  plant  to  plant  hunt- 
ing the  weed.  More  commonly  it  eats  considerable  grass  with  the 
weed,  but  as  the  disease  progresses  it  eats  less  and  less  of  anything. 

Sometimes  a  horse  in  the  earty  stages  of  the  disease  will  be  in  con- 
stant motion,  walking  about  in  a  restless  and  aimless  sort  of  way. 
If  such  a  horse  is  confined  in  a  corral,  it  may  walk  around  the  corral 
constantly,  apparently  never  resting.  As  the  effect  of  the  loco 
increases,  the  animal  loses  flesh,  its  coat  becomes  rough,  and  its  eyes 
staring.  A  horse  in  this  condition  will  stand  hour  after  hour  the 
very  picture  of  dejection,  showing  no  interest  in  anything.  If  ap- 
proached suddenly  it  will  rear,  its  legs  flying  about  in  a  peculiarly 
purposeless  way,  and  perhaps  fall  over  backward.  This  is  well  shown 
in  Plate  V,  figures  2,  3,  and  4. 

A  locoed  horse  when  driven  may  shy  violently  at  some  little  thing, 
and  it  is  dangerous  to  use  such  an  animal.  A  horse  that  becomes 
locoed  after  being  broken  may  become  entirely  unmanageable.  It  is 
impossible  to  lead  it,  back  it,  or  tie  it.  Generally  speaking,  however, 
the  crazy  symptoms  are  not  so  noticeable  as  would  bo  supposed  from 
the  popular  accounts.  Nearly  all  locoed  animals,  when  much  affected, 
are  constipated. 

Cattle  show  the  same  symptoms,  but  none  in  so  marked  a  way.  A 
steer  will  not  rear,  but  a  sudden  noise  will  send  a  tremor  through  its 
whole  body,  and  in  walking  it  shows  the  same  lack  of  muscular  coor- 
dination that  is  seen  in  the  horse.  From  the  fact  that  one  can  ap- 
proach close  to  one  of  these  animals  without  being  noticed,  and  that 
then  the  animals  will  suddenly  rear  and  jump,  it  is  popularly  thought 
that  the  eyesight  is  affected.  It  does  not  appear,  however,  that  there 
is  really  any  defective  vision,  but  that  the  apparent  trouble  with  the 


94  THE   LOCO-WEED   DISEASE   OF   THE   PLAINS. 

eyes  is  simply  due  to  the  general  disorganized  condition  of  the  ner- 
vous system.  Probably  the  trouble  is  mental  rather  than  due  to 
any  difficulty  with  the  eyes,  although  this  is  a  difficult  matter  to 
decide  positively.  It  is  sometimes  difficult  to  lead  a  locoed  animal 
into  a  barn,  as  it  is  apparently  afraid  that  the  door  is  not  high  enough, 
or  it  may  crouch  as  if  to  avoid  something  that  is  not  present  at  all. 
This  is  well  shown  in  Plate  VII,  figures  1  and  2,  where  the  animals  in 
going  through  a  gate  crouch  and  avoid  an  imaginary  wire  or  an  upper 
bar. 

Commonly,  a  locoed  animal  is  dull,  but  under  especially  exciting 
causes  it  may  become  almost  frantic.  This  is  particularly  noticeable 
in  steers  taken  off  the  range,  which  will  sometimes  go  into  paroxysms 
of  rage  and  attack  everything  in  sight.  It  is  almost  impossible  to  drive 
a  locoed  animal.  It  may  run  into  the  horse  of  the  person  driving  it. 
When  started  in  one  direction  it  is  sometimes  almost  impossible  to 
turn  it.  Sometimes  an  animal  after  being  started  will  go  straight 
ahead  at  a  uniform  gait  until  it  strikes  some  obstacle.  If  this  ob- 
stacle happens  to  be  a  wire  fence  it  will  go  through  it,  paying  no  atten- 
tion to  incidental  cuts.  This  would  not  be  so  surprising  in  the  case 
of  a  steer,  for  cattle  under  normal  conditions  will  frequently  go  through 
a  fence  with  little  harm,  but  most  horses  are  afraid  of  barbed-  wire, 
and  even  a  small  cut  will  stop  them.  Not  so  with  locoed  horses; 
they  will  sometimes  rub  along  a  fence,  mangling  themselves,  but  ap- 
parently suffering  no  pain.  The  condition  of  such  a  horse  is  shown 
in  Plate  VIII,  figure  6.  It  is  evident  that  the  nerves  of  sensation  are 
partially  paralyzed.  It  is  noticeable,  too,  that  a  horse  that  has  been 
cured  of  loco  has  permanently  lost  much  of  its  sensitiveness.  The 
whip  and  spur  sometimes  make  very  little  impression,  although  the 
animal  may  have  been  very  sensitive  before  suffering  from  the  loco 
poison. 

In  general,  the  symptoms  in  horses  and  cattle  are  very  much  the 
same.  The  lack  of  muscular  coordination  is  more  noticeable  in  horses, 
as  would  be  expected  from  their  more  delicate  nervous  organization. 
The  head  of  a  locoed  steer  or  cow  will  shake  like  the  hand  of  a  palsied 
man.  Frequently  in  cattle  there  will  be  local  accumulations  of  serum, 
especially  under  the  jaw.  These  are  not  so  likely  to  occur  in  horses. 
Abortion  is  a  common  phenomenon  in  locoed  cows.  By  many 
stockmen  this  loss  of  the  calf  crop  is  sometimes  considered  one  of  the 
most  serious  of  the  effects  of  loco.  As  the  disease  progresses,  the 
animals  eat  less  and  less  and  finally  die  of  starvation. 

Another  symptom  which  was  noticed  in  some  of  the  cattle  was  a 
tetanic  condition  of  some  of  the  flexor  muscles  of  the  hind  limb,  so 
that  the  fetlock  joint  was  flexed  and  the  animal  appeared  to  be 
"standing  on  its  toes."  This  is  shown  in  Plate  X,  figure  5. 


PATHOLOGICAL   LESIONS.  95 

The  symptoms  in  sheep  are  similar  to  those  in  horses  and  cattle, 
but,  as  would  be  expected  from  the  character  of  the  animals,  they 
are  less  noticeable.  The  locoed  sheep  walks  in  a  stiff  way,  staggers, 
and  becomes  weak.  It  lies  down  frequently  and  does  not  keep  up 
with  the  band.  Its  head  may  shake,  although  this  is  not  a  very  com- 
mon phenomenon.  The  herders  say  that  locoed  sheep  are  "foolish" 
or  "crazy,"  and  these  terms  describe  very  well  the  general  appear- 
ance of  the  animals.  Lambs  are  pecu  iarly  susceptible  to  the  influ- 
ence of  the  poison  and  may  succumb  to  it  within  two  or  three  weeks, 
dying  with  very  little  loss  of  flesh. 

It  will  be  remembered  that  in  the  list  of  symptoms  both  high  and 
low  temperatures  were  mentioned.  The  results  of  the  field  work  would 
seem  to  indicate  that  both  classes  of  observers  were  right.  In  some 
locoed  animals  temperatures  as  high  as  106°  or  108°  F.  have  -been 
observed,  and  in  a  few  cases  subnormal  temperatures.  In  a  great 
majority  of  chronic  loco  cases,  however,  the  temperature  does  not 
differ  much  from  the  normal,  and  it  can  be  safely  said  that  chronic 
loco  poisoning  does  not  have  any  distinct  effect  upon  the  body  tem- 
perature. 

PATHOLOGICAL   LESIONS. 

Loco  victims  always  show  marked  anemia.  This  is  indicated  not 
only  by  the  emaciation  and  paleness  of  the  flesh,  but  by  the  excess  of 
serous  fluids  of  the  body  and  by  the  deposits  of  organized  serum  in 
various  parts  of  the  body.  This  is  more  especially  marked  at  the 
base  of  the  ventricle  of  the  heart. 

EXAMINATION    OF    BLOOD. 

Inasmuch  as  all  locoed  animals  show  marked  symptoms  of  general 
anemia,  a  technical  study  of  the  blood  is  of  considerable  interest. 
The  multiplicity  of  general  duties  at  the  station  made  it  impossible 
to  make  any  very  large  number  of  blood  determinations.  Some  counts, 
however,  were  made  in  the  second  and  third  summers  and  the  results 
are  significant.  Little  seems  to  have  been  published  in  regard  to 
the  blood  counts  of  cattle,  and  it  would  have  been  interesting  if 
we  could  have  made  a  large  number  of  counts  of  both  normal  and 
locoed  animals.  The  counts  in  the  summer  of  190(>  were  made  by 
Scientific  Assistant  Klugh,  and  his  work  was  checked  off  by  counts 
made  by  two  other  assistants.  In  1(.M)7  the  blood  counts  were 
made  by  Field  Assistant  Clawson,  and  this  work  was  checked  by 
counts  made  by  two  others. 

The  normal  number  of  reel  corpuscles  for  cattle  at  our  station 
seemed  to  be  something  over  8,000, 000.  This  is  higher  than  recorded 
normals,  but  our  station  was  at  an  altitude  of  nearly  o.OOO  feet,  and 


96 


THE   LOCO-WEED    DISEASE   OF   THE   PLAINS. 


we  would  expect  higher  counts  at  this  elevation.  The  locoed  animals 
examined  in  1906  averaged  5,138,333;  those  examined  in  1907,  21 
in  number,  averaged  7,250,238.  This  apparently  shows  a  wide  dis- 
crepancy. It  is  largely  explained,  however,  by  the  fact  that  those 
examined  in  1906  were  nearly  all  in  the  last  stages  of  the  disease, 
while  most  of  those  examined  in  1907  were  undergoing  treatment 
and  in  some  cases  had  already  made  marked  gains.  These  results 
are  such  as  would  be  expected,  emphasizing  the  fact  of  the  marked 
anemia.  The  following  table  is  significant  as  indicating  the  effect 
of  treatment  upon  locoes,  as  it  shows  in  general  gradual  improvement 
as  the  course  of  treatment  progressed. 

Number  of  red  corpuscles  in  blood  of  number  of  normal  and  locoed  cattle,  the  latter  in 

rarious  stages  of  treatment. 


Xo.  of  animal. 

Treated 
less  than  1 
week. 

Treated  1 
to  4  weeks. 

Treated  4 
weeks  and 
over. 

Not 
locoed. 

Remarks. 

36                                         

6,180,000 

IDied,    bad 

36 

7  580  000 

/    jaw. 

38 

6,000,000 

Bad  case. 

43                                               ... 

8,000,000 

546                  

6,650,000 

546 

9  600  000 

546 

8,840.000 

554                                    

9,917,000 

556  

5,380,000 

556 

8,900  000 

560  

5,930,000 

Died. 

42           .              

6,  979,  000 

361        

7,508,000 

557 

8,520,000 

558                      

6,120,000 

566           

6,810,000 

569 

6  070  000 

557 

8  220  000 

35.                

6.473.000 

Average 

6,511  600 

7  268  000 

8  050  000 

8,000,000 

An  average  of  12  locoes  in  1907  showed  3,735  white  corpuscles. 

Tests  of  hemoglobin  were  made  by  the  Talquist  scale.  Healthy 
animals  varied  from  85  to  98,  the  average  being  between  90  and  95. 
In  the  locoes  examined  in  1906  the  hemoglobin  was  70,  while  in  1907 
it  averaged  85.  The  lowest  observed  in  1907  was  75  and  the  highest 
85.  It  should  be  borne  in  mind,  however,  that  many  of  the  1907 
locoes  were  on  the  road  to  recovery,  and  in  some  cases  were  in  very 
good  condition. 

On  July  21,  1906,  10  healthy  sheep  were  taken  at  random  from  a 
herd  that  were  in  the  shearing  sheds,  and  an  examination  of  hemoglo- 
bin made  by  the  Talquist  method.  The  average  of  these  10  gave 
87.7.  On  the  same  date  an  examination  was  made  of  14  locoed 
sheep,  giving  an  average  of  78. 


PATHOLOGICAL   LESIONS.  97 

WALLS    OF    STOMACH. 

In  nearly  all  locoes  there  is  a  diseased  condition  of  the  stomach.  In 
acute  cases  the  walls  are  very  much  inflamed.  In  chronic  cases  ulcers 
are  commonly  present.  The  ulcers  are  not  so  common  in  the  stom- 
achs of  horses,  but  are  almost  invariably  present  in  the  fourth 
stomachs  of  cattle.  In  sheep  one  is  apt  to  find  inflamed  walls  rather 
than  ulcers. 

In  these  ulcers  a  microscopic  examination  shows  that  the  mucous 
membrance  is  entirely  destroyed.  Sometimes  other  parts  of  the 
alimentary  canal  may  be  inflamed,  or  have  small  ulcers,  but  this  is  not 
a  usual  condition. 

HEMOLYMPH    GLANDS. 

The  hemolymph  glands  are  apparently  much  more  prominent  in 
locoes  than  in  normal  animals.  This  is  especially  noticeable  in  cattle. 
In  these  animals  the  hemolymph  glands  seem  to  be  very  numerous  in 
the  thoracic  cavities,  in  the  connective  tissue  about  the  heart,  and  in 
that  in  front  of  the  thoracic  aorta.  They  are  only  less  noticeable  in 
the  lumbar  region  of  the  abdominal  cavity.  In  the  literature  on  the 
hemolymph  glands  there  seems  to  be  nothing  in  regard  to  the 
question  as  to  whether  numbers  of  these  glands  have  any  pathological 
significance.  Most  of  the  investigations  have  been  directed  to 
physiological  questions.  There  has  been  no  opportunity  for  the 
author  to  make  the  extended  observations  which  would  be  necessary 
to  throw  light  on  this  question.  Preliminary  observations  on  a  con- 
siderable number  of  animals  in  slaughterhouses  make  it  seem 
probable,  however,  that  the  normal  number  is  much  smaller  than  in 
the  case  of  locoes,  and  it  seems  possible  that  the  condition  of  chronic 
anemia  in  these  poisoned  animals  may  be  correlated  with  the  number 
of  hemolymph  glands. 

NERVOUS    SYSTEM. 

The  central  nervous  system  is  generally  in  a  hyperemic  or  con- 
gested condition.  In  a  few  cases  clots  were  found  in  the  lateral 
ventricles  of  the  brain.  We  have  never,  however,  found  clots  in  the 
fourth  ventricle,  although  this  has  repeatedly  been  said  to  have  been 
the  case  by  the  earlier  observers  of  loco  phenomena. 

The  serous  exudate  in  the  epidural   space  is  especially  abundant 

and  is  more  or  less  organized.     Commonly  it  is  particularly  abundant 

about  the  points  of  exit  of  the  spinal  nerves.     This  condition  is  rarely 

absent  in  chronic  locoes.     It  seems  probable  that  the  pressure  of  this 

79154— Bull.  112—09 7 


98  THE   LOCO-WEED    DISEASE    OF   THE   PLAINS. 

coagulated  serum  may  be  the  cause  of  many  of  the  nervous  symptoms 
which  are  pronounced  in  loco  victims.  In  some  cases  this  coagulated 
serum  is  especially  abundant  in  the  lumbar  region,  and  it  might  well 
be  the  cause  of  the  partial  paralysis  of  the  hind  limbs,  which  is  fre- 
quently very  marked. 

In  locoed  cows  and  mares,  generally  speaking,  the  ovaries  are  found 
to  be  more  or  less  diseased.  They  are  generally  small  and  hard,  and 
frequently  contain  serous  cysts.0 

In  a  number  of  cases  it  was  found  that  the  kidneys  were  somewhat 
diseased.  This  was  not,  however,  the  condition  of  the  majority  of 
the  cases,  and  would  not  seem  to  be  typical  of  loco  poisoning. 

VIRULENCE  OF  LOCO  POISON. 
TIME    REQUIRED   TO    PRODUCE    POISONING. 

Previous  authors  vary  greatly  in  regard  to  the  length  of  time  taken 
for  loco  to  affect  animals.  Some  say  that  it  takes  only  a  few  days; 
others  that  the  poison  may  be  several  years  in  producing  marked 
effects.  Our  work  seems  to  show  that  small  amounts  of  the  weed 
produce  no  appreciable  effect,  and  that  the  poison  is  cumulative,  so 
that  the  apparent  results  come  quite  suddenly  after  a  period  when  the 
animal  does  not  appear  to  be  affected  at  all.  The  time  from  the 
beginning  of  the  feeding  to  death  in  the  animals  experimented  upon 
varied  from  two  months  and  eight  days  to  six  months  and  nine  days. 
It  might  be  expected  that  there  would  be  much  variation  in  the  time, 
because  it  is  impossible  to  secure  uniformity  in  conditions.  There 
is  a  great  difference  in  the  individual  susceptibility  to  the  poison,  and 
when  animals  are  in  the  pasture  some  eat  a  very  much  larger  amount 
of  the  loco  than  do  others.  When  fed  in  the  corral,  too,  on  a  mixture 
of  loco  and  other  feed,  there  will  be  an  individual  difference  in  the 
relative  amount  of  loco  eaten.  Of  the  1905  cattle  dying  of  loco,  the 
average  length  of  life  after  the  feeding  was  begun  was  five  months 
and  six  days.  Of  these,  No.  12,  which  was  fed  partly  in  the  corral, 
died  in  three  months  and  thirteen  days.  Of  the  other  four,  two  died 
in  six  months  and  five  days,  and  one  in  six  months  and  four  days. 
This  would  seem  to  indicate  that  the  corral-fed  animals  succumbed 
the  more  quickly.  In  this,  as  in  other  cases,  we  must  bear  in  mind, 
however,  that  while  doubtless  the  corral-fed  animals  ate  more  loco, 
they  may  also  have  suffered  somewhat  from  confinement  and  from 
an  actual  lack  of  proper  food.  This  doubtless  was  true  in  the  case  of 

o  Dr.  John  R.  Mohler,  chief  of  the  Pathological  Division  of  the  Bureau  of  Animal 
Industry,  calls  attention  to  the  fact  that  a  cystic  condition  of  the  ovaries  is  a  com- 
mon condition  in  the  horses  and  cattle  of  the  West,  and  that  this  condition  may  not 
be  due  to  the  specific  effect  of  the  loco  poison. 


VIRULENCE   OF   LOCO   POISONING.  99 

some  of  the  animals  of  the  first  year.  Then,  too,  generally  speaking, 
when  animals  were  first  taken  into  the  corral  they  were  starved  to 
give  them  an  appetite  for  loco.  In  other  cases  some  were  fed  loco 
exclusively  for  many  days.  This  treatment  doubtless  would  occasion 
considerable  losses. 

Of  the  1905  horses  the  average  length  of  life  after  commencing  to 
eat  loco  was  three  months  and  seventeen  days ;  those  eating  Aragallus 
lamberti  lived  three  months  and  nineteen  days ;  those  eating  Astraga- 
lus mollissimus  lived  two  months  and  ten  days. 

In  1906  cattle  lived  on  the  average  three  months  and  seventeen 
days ;  the  corral-fed  lived  three  months  and  four  days ;  the  pasture- 
fed  lived  three  months  and  seventeen  days.  The  horses  lived  four 
months  and  nineteen  days ;  the  horses  eating  Aragallus  lamberti  lived 
four  months  and  twenty-four  days ;  those  eating  Astragalus  mollissi- 
mus lived  three  months  and  fourteen  days.  Those  in  the  Aragallus 
lamberti  pasture  lived  four  months  and  twenty-eight  days;  those  fed 
on  Aragallus  lamberti  in  corral  lived  four  months  and  twelve  days. 

It  will  thus  be  seen  that  in  the  first  year  the  horses  died  sooner 
than  the  cattle,  while  in  the  second  year  the  cattle  lived  the  shorter 
time.  This  difference  in  results  I  will  not  attempt  to  explain  fully. 
It  may  be  said,  however,  that  in  the  season  of  1905  more  of  the 
horses  than  of  the  cattle  were  fed  in  the  corral,  and  doubtless  they 
suffered  more  from  shortness  of  feed,  especially  as  some  of  them  were 
for  a  time  fed  on  loco  exclusively.  In  the  season  of  1906  one  of  the 
cattle  had  eaten  loco  during  the  latter  part  of  the  preceding  season, 
but  this  time  was  not  taken  into  account  in  the  tabulation  of  the 
averages.  This  reduced  the  average  of  the  cattle  somewhat.  Then 
there  is  reason  to  think  that  some  of  the  second  season's  cattle  were 
peculiarly  susceptible  to  the  poison.  The  cattle  during  the  second 
season  ate  much  more  freely  of  the  weed  than  did  the  horses.  It 
must  be  recognized  that  the  number  of  our  cases  is  not  large  enough 
so  that  we  can  place  implicit  reliance  on  averages.  All  we  can  say 
is  that  the  results  are  significant,  but  must  be  interpreted  very 
carefully. 

The  animals  eating  Astragalus  mollissimus  died  more  quickly  than 
those  eating  Aragallus  lamberti.  Of  the  horses  of  1905,  those  eating 
Aragallus  lamberti  died  in  three  months  and  nineteen  days;  those 
eating  Astragalus  mollissimus  in  two  months  and  ten  days.  Of  the 
horses  of  1906,  the  one  that  was  fed  Astragalus  mollisxinivs  died  in 
three  months  and  fourteen  days,  while  those  eating  Aragalhis  lamberti 
died  in  four  months  and  twenty-four  days. 

The  work  upon  sheep  was  of  such  a  character  that  no  general  con- 
clusions can  be  drawn  as  to  the  length  of  time  for  the  poison  to  take 
effect. 


100  THE  LOCO- WEED   DISEASE   OF   THE  PLAINS. 

Horses  and  cattle  feeding  freely  and  continuously  upon  AragaUus 
lamberti  may  live  from  three  to  six  months.  Horses  feeding  freely 
and  continuously  upon  Astragalus  mollissimus  are  not  likely  to  sur- 
vive longer  than  from  two  to  four  months.  The  fatal  issue  of  the 
habit  may  be  put  off  almost  indefinitely,  however,  in  the  case  of  the 
moderate  eater.  It  may  live  a  year  or  several  years,  but  it  greatly 
deteriorates. 

During  the  third  season  none  of  the  animals  were  fed  in  the  corral, 
but  all  were  kept  in  a  pasture  where  they  had  an  abundance  of  grass, 
and  they  were  not  forced  upon  the  loco  except  that  they  were  held  a 
part  of  the  time  where  loco  was  abundant.  As  soon  as  they  showed 
evident  symptoms  of  being  poisoned  they  were  taken  up  for  treatment 
instead  of  being  permitted  to  go  through  the  whole  course  of  the  loco 
disease,  as  in  preceding  seasons.  An  attempt  was  made  to  preserve 
life  as  long  as  possible  and  to  produce  cures  when  practicable.  The 
natural  result  of  these  conditions  was  that  the  animals  yielded  to  the 
poison  much  more  slowly  than  in  the  preceding  season.  Another 
fact  had,  doubtless,  some  influence,  namely,  that  the  animals  were 
in  most  cases  the  survivors  of  preceding  experiments  and  were  origi- 
nally more  or  less  immune  to  the  effects  of  the  loco. 

AMOUNT    OF    LOCO    NECESSARY   TO    PRODUCE    POISONING. 

The  limitations  of  the  field  work  and  the  comparatively  small  num- 
ber of  animals  experimented  upon  make  it  impossible  to  state  with  any 
definiteness  how  much  loco  an  animal  must  eat  before  showing  symp- 
toms of  the  poison.  In  all  cases  some  pasture  feeding  was  given  to  the 
animals  kept  in  the  corrals  in  order  to  give  them  suitably  healthful 
conditions  of  life.  When  in  the  pasture,  some  would  eat  loco  in  con- 
siderable abundance,  while  others  would  devote  themselves  wholly 
or  in  a  very  large  part  to  grass.  It  was  our  custom  to  put  these  ani- 
mals into  pasture  at  least  one  day  in  the  week.  It  is  to  be  presumed, 
too,  that  the  amount  of  hay  eaten  while  they  were  in  the  corrals 
would  make  some  difference  in  the  effect  of  the  poison,  and  thus  bring 
hi  wide  individual  variations. 

Because  of  the  small  number  of  animals  it  was  possible  to  subject 
only  a  few  to  a  single  line  of  treatment.  In  most  cases  each  animal 
was  a  subject  of  several  phases  of  the  experiment.  The  amount  of 
loco  fed  in  the  corrals,  however,  was  weighed  and  a  record  kept  for 
each  animal.  From  these  records  we  can  make  a  rough  estimate  of 
the  amount  eaten  before  the  symptoms  of  loco  became  evident. 
From  these  records  it  appears  that  about  400  pounds  of  AragaUus 
lamberti  will  loco  the  average  horse  or  steer. 


RELATIVE  IMPORTANCE   OP   SPECIES  INVESTIGATED.  101 


RELATIVE     IMPORTANCE     OF    ASTRAGALUS     MOLLISSIMUS    AND 
ARAGALLUS  LAMBERTI. 

The  tentative  conclusions  reached  at  the  end  of  the  first  year  in 
regard  to  the  effects  of  Aragallus  lamberti  and  Astragalus  moUissimus 
were  amply  confirmed  by  the  work  of  the  second  and  third  years. 
Astragalus  moUissimus  is  harmful  only  to  horses.  The  loss  of  cattle 
from  this  plant  is  inconsiderable.  This  is  not  because  the  cattle  can 
not  be  affected  by  the  poison,  but  because  they  do  not  eat  the  weed. 
It  was  found  in  the  corral  experiments  almost  impossible  to  make 
cattle  eat  this  species  even  when  they  were  starved  to  it.  Generally 
they  would  starve  to  death  rather  than  take  to  it.  So  far  as  our 
experiments  went,  it  may  be  said  that  cattle  never  eat  Astragalus 
moUissimus.  In  regions  where  this  weed  prevails,  and  not  Aragallus 
lamberti,  locoed  cattle  are  almost  unknown.  Examples  of  this  are 
the  regions  about  Holyoke,  Colo.,  and  Imperial,  Nebr.  The  same 
thing  is  reported  in  the  Astragalus  moUissimus  region  in  the  Pan- 
handle of  Texas.  About  Santa  Rosa,  N.  Mex.,  where  the  damage  is 
commonly  ascribed  to  Astragalus  moUissimus,  it  is  true,  the  author 
was  told  that  possibly  10  per  cent  of  the  cattle  and  50  per  cent  of  the 
horses  were  lost  annually.  It  would  appear  that  perhaps  Astragalus 
moUissimus  was  responsible  for  the  loss  of  the  cattle  in  this  locality. 
The  locoes  of  this  neighborhood,  however,  have  not  been  examined 
with  any  care,  and  it  is  possible  that  plants  other  than  Astragalus 
moUissimus  are  responsible  for  the  cattle  loss.  Our  experience 
showed  that  not  only  would  the  cattle  not  eat  Astragalus  moUissimus, 
but  that  horses  were  not  likely  to  take  to  it  except  because  of  scarcity 
of  other  food. 

It  is  very  different  with  Aragallus  lamberti;  not  only  horses,  but  also 
cattle  and  sheep,  eat  this  readily.  They  are  more  likely  to  eat  it 
during  a  scarcity  of  other  food,  but  they  will  not  only  continue  to  eat 
it  when  other  food  is  abundant,  but  may  begin  the  habit  at  any  time 
of  the  year.  Of  course  they  are  more  likely  to  start  eating  the  loco 
in  the  winter  and  early  spring  and  in  the  fall  when  the  loco  is  green 
and  succulent  and  the  grass  is  dry.  But  even  in  midsummer,  when 
supplied  with  abundant  pasturage,  if  thrown  in  contact  with  loco 
plants  they  may  eat  considerable  amounts  -enough,  even,  to  produce 
fatal  results.  Cattle  eat  Aragallus  lamberti  much  more  readily  than 
do  horses.  Nearly  all  cattle  will  eat  it  more  or  less,  and  a  large  pro- 
portion will  contract  the  habit.  A  great  many  horses,  on  the  other 
hand,  will  not  touch  it  even  if  run  upon  ranges  covered  with  the 
weed.  Consequently  the  loss  of  cattle  from  AmpaUux  lamberti  is 
much  greater  than  that  of  the  horses. 

Sheep,  too,  eat  Aragallus  lamberti  very  readily.  It  is  always  con- 
sidered a  misfortune  to  have  a  few  sheep  commence  eating  the  weed, 


102  THE  LOCO-WEED   DISEASE   OF   THE  PLAINS. 

for  sheep  are  such  imitative  creatures  that  a  few  may  lead  a  whole 
band  astray.  Some  sheepmen  immediately  cut  the  throats  of  loco 
eaters  on  this  account. 

The  symptoms  of  poisoning  from  AragaUus  lamberti  are  like  those 
from  Astragalus  mottissimus,  but  the  effect  does  not  come  so  quickly. 
The  laboratory  work  conducted  by  Doctor  Crawford  has  established 
the  fact  of  the  greater  toxicity  of  Astragalus  mollissimus.  However, 
vastly  the  greater  amount  of  damage  is  done  by  AragaUus  lamberti 
because  it  is  eaten  so  much  more  readily,  and  because  it  affects  cattle 
and  sheep  as  well  as  horses.  Our  pasture  experiments  all  go  to  show 
that  most  horses  when  kept  where  AragaUus  lamberti  is  abundant 
will  sooner  or  later  yield  to  the  poison,  and  that  the  cattle  succumb 
much  more  quickly  to  the  attractions  of  the  weed. 

SUSCEPTIBILITY  OF  DIFFERENT  BREEDS. 

Sheepmen  are  unanimous  in  saying  that  the  blackfaces  are  much 
more  susceptible  than  the  Merinos.  This  statement  was  abundantly 
confirmed  by  our  observations. 

In  regard  to  cattle  and  horses,  it  is  a  matter  of  common  observa- 
tion among  stockmen  that  the  better  bred  animals  are  more  likely 
to  become  locoed.  They  explained  this  in  part,  and  probably 
reasonably,  by  the  fact  that  animals  accustomed  to  be  taken  care 
of  do  not  know  how  to  "  rustle, "  and  consequently  take  the  food 
that  comes  first  instead  of  hunting  for  better  material.  Reliable 
stockmen  tell  me  that  Durhams  are  more  easily  affected  than  Here- 
fords.  When  our  experiments  started  in  Hugo,  an  old  stockman 
remarked  that  two  black  steers  in  our  herd  would  be  the  first  to  be 
affected,  saying  that  this  would  be  true  not  because  of  their  color 
but  because  they  were  of  better  blood.  The  result  showed  the 
accuracy  of  his  prophecy,  for  the  black  ones  were  the  first  to  suc- 
cumb. While  we  had  a  number  of  different  breeds  among  our 
experimental  animals,  the  numbers  were  not  large  enough  for  any 
general  conclusions  to  be  drawn.  The  experiments  would  indicate, 
however,  that  Herefords  are  decidedly  less  susceptible  than  Aberdeen- 
Angus  cattle.  The  one  steer  of  our  herd  that  refused  to  eat  any  con- 
siderable amount  of  the  loco  was  a  scrub.  In  Colorado  generally  I 
saw  more  locoed  Herefords  than  of  any  other  breed,  but  this  is 
doubtless  explained  by  the  fact  that  this  is  the  most  popular  breed 
of  range  cattle. 

AGE    SUSCEPTIBILITY. 

Marshall  (1904)  states  that  loco  poisoning  appears  only  in  young 
sheep,  generally  speaking;  never  in  those  over  2  years  old.  Blank- 
inship  (1903)  states  that  only  young  sheep  and  colts  are  affected. 
Older  sheep  and  horses  rarely  acquire  the  habit.  Our  experiments 


EFFECT  OF  LOCO  ON  VARIOUS  ANIMALS.  103 

in  Colorado  show  that  while  lambs  suffer  in  an  acute  way  from  loco, 
the  older  sheep  are  by  no  means  free  from  the  disease. 

In  cattle  and  horses  we  had  a  general  impression  of  the  greater 
susceptibility  of  the  younger  ones,  but  this  was  hardly  borne  out  by 
the  facts.  There  seemed  to  be  very  little  difference  in  the  time 
taken  to  kill,  whether  the  animals  were  young  or  old.  We  could 
determine  but  little  about  this  in  the  first  season's  work,  for  most  of 
the  stock  were  young  animals.  During  the  second  and  third  seasons, 
however,  we  had  a  number  of  old  animals,  especially  among  the 
horses,  and  there  was  no  clear-cut  difference  in  susceptibility  to  the 
poison  because  of  difference  of  age.  As  is  intimated  elsewhere,  there 
is  a  difference  in  individual  susceptibility  which  must  always  be  taken 
into  account. 

The  apparently  greater  susceptibility  of  young  animals,  as  noticed 
by  other  observers,  may  be  due  in  part  to  the  fact  that  there  are 
more  young  animals  than  older  ones,  and  hence  apparently  a  greater 
number  of  cases  among  the  young  animals,  and  partly  to  the  fact 
that  many  of  the  old  animals  are  those  that  have  survived  because 
of  an  individual  lack  of  susceptibility  to  the  temptations  of  the  plant. 

EFFECT  ON  ANIMALS  OTHER  THAN  HORSES,  CATTLE,  AND 

SHEEP. 

We  found  it  very  difficult  to  get  evidence  of  the  effect  of  loco  on 
mules.  Some  stockmen  reported  that  they  had  seen  locoed  mules, 
while  others  said  that  mules  were  not  affected.  Considerable  interest, 
therefore,  attached  to  observations  of  the  two  mules  which  formed  a 
part  of  our  experiment  in  1906.  Unfortunately,  both  were  old  ani- 
mals, and  the  poorest  one  died  of  old  age.  The  other,  however,  was 
a  fairly  healthy  animal  and  its  death  proved  conclusively  that  mules 
could  be  locoed. 

In  the  summer  of  1907  a  locoed  mule  was  brought  in  to  the  station 
for  treatment.  It  had  the  typical  symptoms  of  loco  poison.  Its 
insensibility  to  barbed-wire  fence  cuts  was  especially  marked,  for  it 
would  run  against  a  fence  and  rub  itself  along  for  two  or  three  lengths, 
the  wire  cutting  through  the  skin  and  into  the  muscle,  but  apparently 
occasioning  no  pain.  When  started  up  in  the  pasture  it  would  trot 
along  at  a  slow  gait  in  almost  a  straight  line,  going  for  a  long  distance, 
sometimes  until  some  obstruction  in  its  way  would  stop  it.  This 
was  an  old  animal,  and  while  it  would  eat  fairly  well  and  we  found  it 
possible  to  dose  it,  it  succumbed,  probably  from  the  combined  influ- 
ence of  old  age  and  the  loco  poison.  There  seems  no  longer  any 
question  in  regard  to  the  possibility  of  mules  becoming  locoed  by 
eating  AragaXLus  lamberti.  It  does  not  appear,  however,  that  they 
are  as  liable  to  take  to  the  plant  as  are  horses. 


104  THE  LOCO-WEED  DISEASE  OP  THE  PLAINS. 

In  regard  to  other  domestic  animals  and  wild  animals,  the  testi- 
mony is  conflicting,  and  it  is  impossible  now,  with  the  evidence  at 
hand,  to  pass  on  it.  Some  stockmen  say  that  they  have  seen  locoed 
antelopes.  Others  say  that  antelopes  are  not  affected.  Inasmuch, 
however,  as  there  is  no  record  of  feeding  experiments  on  antelopes, 
we  must  consider  the  matter  as  still  an  open  question.  Doctor  Craw- 
ford's pharmacological  work  shows  that  rabbits  are  affected,  and  it 
must  be  presumed  that  other  herbivorous  animals  may  be  susceptible 
to  the  poison  of  the  weed.  One  reputable  stockman  told  me  of  a 
man  who  fed  cut  loco  to  a  lot  of  pigs,  thinking  it  would  be  good  for 
them,  and  locoed  them  all.  The  writer  has  even  heard  of  locoed 
hens. 

EFFECT  ON   MAN. 

There  are  many  stories  of  men  poisoned  from  eating  loco,  but 
none  of  these  can  be  authenticated.  As  a  matter  of  fact,  inasmuch 
as  our  work  on  horses,  cattle,  and  sheep  shows  that  the  poison  is 
very  slow  in  taking  effect  and  that  an  animal  can  eat  the  weed  for 
quite  a  long  time  without  any  apparent  harmful  results,  it  seems 
unlikely  that  men  have  eaten  enough  to  show  the  results  of  the 
poison.  Pilgrim  in  1898  investigated  a  case  which  was  brought  into 
the  Hudson  River  State  Hospital,  and  concluded  that  the  cause  was 
syphilis.  The  story  by  Janvier  in  Scribner's  Magazine,  Volume  I, 
page  67,  entitled  "In  Mexico,"  which  is  frequently  quoted  in  this 
connection,  was  based  on  the  properties  not  of  the  loco  plant,  but  of 
stramonium. 

LOSSES  FROM  LOCO  POISONING. 

Attempts  have  been  made  to  get  some  estimate  of  the  losses  from 
loco  poisoning,  but  it  is  impossible  to  make  more  than  the  rudest 
kind  of  conjecture.  An  intelligent  horseman .  near  Wray,  Colo., 
estimated  in  1905  a  loss  of  3  per  cent  of  the  horses.  One  man  near 
Holyoke  in  1906  lost  from  12  to  20  per  cent  of  the  horses  in  one  herd; 
another  in  the  same  locality  in  1905  lost  practically  all  his  horses. 
The  winter  of  1906  was  especially  disastrous  in  New  Mexico  and 
Arizona.  One  man  in  the  Estancia  Valley  in  New  Mexico  lost  50 
per  cent  of  his  horses.  A  conservative  stockman  near  Santa  Rosa, 
N.  Mex.,  estimated  that  during  one  winter  50  per  cent  of  the  horses 
and  10  per  cent  of  the  cattle  perished.  Around  Jerome  Junction, 
Ariz.,  the  estimated  loss  in  the  winter  of  1906  was  from  30  to  60 
per  cent,  and  correspondingly  large  losses  were  said  to  have  taken 
place  about  Flagstaff,  Ariz.  Blankinship  says  that  in  some  parts 
of  Montana  the  loss  of  lambs  reaches  as  high  as  50  per  cent.  It 
has  been  estimated  that  the  annual  money  loss  in  Colorado  is  between 
$1,000,000  and  $2,000,000. 


DESTRUCTION   OF  LOCO  WEEDS.  105 

The  death  loss,  however,  may  not  be  the  largest  factor  in  the 
account.  The  loss  from  deterioration  of  stock  and  from  premature 
sales  is  very  heavy.  Many  stockmen,  when  their  herds  commence 
to  eat  loco,  sell  out  rather  than  run  the  risk  of  having  a  lot  of  locoed 
animals  on  their  hands,  and  this  loss  means  a  very  large  reduction 
in  their  profits.  This,  of  course,  is  a  loss  that  it  is  impossible  to  make 
any  estimate  of.  In  many  cases  stockmen  have  been  driven  out  of 
the  business  by  the  weed,  and  have  even  gone  into  bankruptcy.  In 
some  sections  of  Colorado,  I  am  told,  there  are  not  more  than  one- 
fifth  of  the  animals  on  the  range  that  were  found  a  few  years  ago, 
and  this  reduction  of  numbers  is  entirely  on  account  of  the  loco. 
When  it  is  remembered  that  these  losses  occur  more  or  less  widely 
through  the  semiarid  region  from  the  Canadian  Provinces  to  Mexico, 
it  will  be  seen  that  the  total  loss  from  these  plants  is  extremely  large. 

DESTRUCTION  OF  LOCO  WEEDS. 

The  question  is  naturally  raised  as  to  whether  some  means  can 
not  be  devised  of  exterminating  loco  weeds  from  the  range.  The 
most  obvious  wray  of  doing  this  is  by  cutting  them  out.  This  is 
entirely  feasible  if  the  land  is  worth  the  price  of  the  work.  There 
is  an  erroneous  idea  among  many  of  the  stockmen  that  plants  will 
grow  from  any  part  of  the  root,  and  that  cutting  the  plants  is  useless 
unless  the  whole  root  is  dug  up.  While  the  plant  is  a  perennial,  the 
buds  are  all  at  the  crown,  and  if  tlu's  is  cut  off  the  plant  is  destroyed. 
This  is  brought  out  by  Professor  Blankinship  very  clearly  in  liis 
paper  of  1906.  Actual  experiments  in  Hugo  in  connection  with  our 
loco  work  there  have  proved  the  correctness  of  this  view.  Inas- 
much as  all  the  seeds  do  not  germinate  the  first  year,  of  course  it  is 
necessary  to  repeat  the  cutting  in  successive  years,  but  that  it  is 
entirely  possible  to  clear  pastures  of  the  loco  there  is  no  doubt. 

Doubtless  much  can  be  accomplished  by  the  use  of  a  mowing 
machine  at  the  time  of  flowering.  The  flower  scapes  of  AragaUus 
lamberti  are  erect  and  a  machine  would  cut  out  most  of  them  and 
thus  spoil  the  seed  crop.  The  work  of  cutting  out,  however,  is  not 
as  laborious  as  one  might  think,  and  it  is  very  effective. 

At  the  present  time  the  most  efficient  way  of  combating  the  loco 
seems  to  be  to  cut  it  out.  Where  pastures  are  fenced  in  this  can  be 
done  very  easily.  Astragalus  mottissimus  is  much  more  easily  cut 
out  than  AragaUus  lamberti,  as  it  grows  in  patches  and  rarely  in  any 
very  large  amount.  On  the  open  range,  of  course,  this  method  of 
exterminating  the  loco  is  impracticable. 

In  many  cases  much  can  l>e  accomplished  by  keeping  animals 
away  from  ranges  covered  with  loco  during  the  time  when  feed  is 


106  THE  LOCO-WEED   DISEASE   OP  THE  PLAINS. 

short,  inasmuch  as  they  are  much  more  likely  to  contract  the  habit 
when  other  food  is  lacking.  Sometimes  it  may  be  profitable  to 
feed  for  a  short  time,  in  order  that  the  habit  may  not  be  formed. 

The  question  was  raised  whether  it  might  not  be  possible  to  kill 
out  the  loco  plants  by  chemical  means,  that  is,  to  use  some  sub- 
stance that  would  kill  the  loco  without  injuring  the  grass.  Although 
the  prospect  was  not  very  hopeful,  it  seemed  worth  while  to  try 
the  experiment.  Plots  of  land  were  laid  out  with  suitable  control 
plots,  and  experiments  were  made  by  sprinkling  with  varying 
strengths  of  ammonium  sulphate,  copper  sulphate,  and  iron  sulphate. 
From  the  use  of  ammonium  sulphate  and  copper  sulphate  there 
were  no  good  results;  if  anything  the  loco  seemed  to  grow  more 
luxuriantly.  It  at  first  appeared  that  certain  strengths  of  copperas 
were  giving  the  desired  results;  the  leaves  of  the  loco  were  killed 
while  the  grasses  were  uninjured.  The  thing  appeared  so  hopeful 
that  an  experiment  on  a  larger  scale  was  attempted,  and  a  consid- 
erable patch  of  ground  on  the  ranch  of  Mr.  Mclntyre,  near  Hugo, 
was  treated  in  the  fall  and  left  over  winter,  and  then  treated  again 
in  the  spring.  It  was  thought  that  by  this  extended  treatment  it 
would  be  possible  to  determine  whether  the  poisoning  was  effective 
or  not.  The  result  was,  however,  disappointing,  and  it  was  evident 
that  these  substances  could  not  be  relied  upon  as  exterminators  of 
the  plant. 

INSECTS    DESTROYING    LOCO    PLANTS.0 

A  large  number  of  more  or  less  destructive  insects  are  found  in 
the  loco  plants.  Of  this  number  the  larvae  of  Walshia  amorphella, 
a  small  moth,  and  those  of  Euxesta  notata,  a  minute  fly,  are  especially 
active.  They  not  only  bore  in  the  roots,  but  ascend  into  the  leaf 
stems  and  flower  scapes,  and  when  very  abundant  kill  large  numbers 
of  the  plants.  In  1905  it  was  noticed  than  an  especially  luxuriant 
loco  pasture,  where  the  Astragalus  mollissimus  grew  in  large  bunches 
over  a  considerable  area,  was  practically  cleared  of  the  plants  in 
less  than  a  month's  time,  and  during  the  remainder  of  the  season 
and  through  the  summers  of  1906  and  1907  very  few  plants  were 
found  there.  All  along  the  line  of  the  southern  branch  of  the  Union 
Pacific  Railroad  in  1906  and  1907  there  was  a  general  destruction  of 
Astragalus  mollissimus.  There  were  few  large  plants,  most  of  those 
found  being  small,  and  in  many  cases  they  died  early  in  the  season. 
It  is  noticed,  too,  that  these  larvae  work  so  early  in  the  season  as  very 
largely  to  kill  the  plants  before  the  seeds  are  matured. 

a  The  insects  mentioned  under  this  heading  have  been  identified  by  Dr.  F.  H. 
Chittenden,  of  the  Bureau  of  Entomology  of  the  United  States  Department  of  Agri- 
culture, and  a  paper  on  the  insects  known  to  infest  the  loco  weeds  has  been  published 
as  Bulletin  64,  Part  V,  new  series,  of  that  Bureau  (pages  33^12). 


INSECTS  DESTROYING  LOCO  PLANTS.  107 

From  conversations  with  observant  stockmen  it  appears  that 
Astragalus  moUissimus  comes  and  goes  in  cycles.  Probably  the  insects 
increase  to  such  an  extent  as  to  destroy  the  loco;  then,  because  food 
is  lacking,  the  insects  largely  die  out,  only  to  reappear  again  when  the 
loco  gets  another  good  start. 

The  same  larvae  live  in  AragaUus  lamberti,  but  never  seem  to  do  so 
destructive  work  in  this  plant. 

The  question  naturally  arises  whether  these  insects  can  not  be 
encouraged  and  carried  from  place  to  place  in  order  to  exterminate 
the  loco  plants  in  other  areas.  In  the  summer  of  1906  the  question 
of  colonizing  the  insects  was  raised  in  connection  with  our  experi- 
mental work,  but  it  was  hardly  deemed  practicable.  An  examination 
of  the  more  luxuriant  loco  pastures  of  western  Nebraska  showed 
that  the  insects  were  already  there,  and  were  likely  to  increase  as 
rapidly  as  they  would  if  we  lent  any  additional  aid.  It  appears 
probable  from  our  observations  in  Colorado  that  the  insects,  at  the 
present  time,  have  put  in  their  work  so  effectively  that  Astragalus 
moUissimus  is  likely  to  be  not,  perhaps,  a  rare  plant,  but  very  much 
reduced  in  numbers  for  possibly  from  two  to  five  years. 

The  grub  of  Cleonus  quadrilineata  is  especially  destructive  to 
AragaUus  lamberti.  A.  B.  Clawson,  field  assistant  in  1907,  spent 
considerable  time  in  studying  the  wrork  of  this  insect,  and  while 
his  work  is  necessarily  incomplete  it  is  sufficient  to  indicate  that 
this  is  one  of  the  most  important  factors  in  keeping  down  the  num- 
bers of  the  AragaUus  lamberti  plants.  The  larva  of  this  beetle  when 
mature  is  very  noticeable  when  one  digs  up  the  plants  of  AragaUus 
lamberti  by  the  roots.  It  is  a  large  white  grub,  and  either  lives  in 
the  roots  or,  in  many  cases,  burrows  in  the  outside  of  the  root  of  the 
plants.  It  was  found  in  abundance  as  early  as  the  latter  part  of 
June.  Perhaps  more  were  found  working  upon  the  surface  of  the 
root,  but  in  many  cases  they  worked  inside  and  destroyed  a  large 
part  of  the  root  of  the  older  plants.  It  was  noticed  about  the  end  of 
the  first  week  in  July  that  the  pupae  were  being  found  in  the  cases. 
These  cases  were  apparently  made  largely  of  dirt  and  are  commonly 
found  on  the  side  of  the  root,  partly  occupying  spaces  which  had 
been  eaten  out  by  the  grub.  The  cases  are  about  20  to  25  mm. 
long  by  perhaps  half  that  in  width,  being  irregularly  oval  in  shape. 

The  first  adult  beetles  were  noticed  coming  from  the  pupal  cases 
toward  the  end  of  July.  At  this  time  and  during  the  first  part  of 
August  the  adults  were  quite  fairly  abundant.  Just  how  much  dam- 
age these  grubs  do  to  AragaUus  lamberti  it  is  difficult  to  say.  Certainly 
they  do  not  kill  out  the  plants  so  thoroughly  as  those  insects  which 
infest  Astragalus  moUissimus.  Their  main  work  seems  to  be  confined 
to  the  older  plants,  and,  without  any  question,  they  hasten  the  death 
of  these  plants.  In  some  pastures  where  the  AragaUus  lamberti  had 


108  THE  LOCO- WEED   DISEASE   OF   THE  PLAINS. 

grown  into  unusually  large  plants,  it  was  noticed  that  they  were  all 
being  destroyed.  The  chief  work  of  the  larva  seems  to  be  in  limiting 
the  number  of  years  during  which  the  plants  may  live. 

It  should  be  noted  in  this  connection  that  the  most  destructive 
work  of  this  insect  comes  after  the  period  of  flowering  and  seed 
formation,  so  that  even  when  plants  are  killed  they  have  already 
produced  the  annual  crop  of  seed. 

EFFECT  OF  DRY  SEASONS. 

It  is  a  matter  of  common  remark  among  stockmen  that  the  loco 
weeds  are  most  abundant  in  wet  seasons.  This  is,  doubtless,  because 
the  seeds  have  a  water-resisting  coat  and  do  not  germinate  except 
under  favorable  conditions.  Experimental  attempts  to  raise  loco 
weeds  have  shown  this  to  be  the  case.  Mr.  V.  K.  Chesnut  tells  me 
that  in  Montana  it  was  three  years  before  they  had  a  crop  from  sow- 
ing the  seeds.  Our  own  experiments  gave  similar  results.  It  is 
not  known  how  long  the  seeds  will  remain  viable,  but  it  is  certainly 
several  years. 

During  the  past  dry  seasons  in  Colorado  the  loco  plants  have 
almost  disappeared  in  some  sections,  this  being  probably  due  to 
the  combined  influence  of  insects  and  meteorological  conditions. 
The  insects  have  destroyed  the  old  plants,  and  because  of  lack  of 
favorable  conditions  for  germination,  new  ones  have  not  come  in  to 
take  their  place. 

REMEDIES. 

From  the  characteristics  of  the  loco  disease  and  its  diagnosis,  it  is 
seen  that  it  is  the  result  of  long-continued  feeding.  In  most  cases 
the  amount  of  the  plant  eaten  at  any  one  time  is  small,  much  more 
being  eaten  of  the  grasses  than  of  the  loco.  The  effects  of  the 
poison  in  the  more  acute  cases  do  not  appear  under  about  two  weeks, 
and  in  most  of  the  adults  only  after  weeks  and  even  months  of  feed- 
ing. Only  very  small  doses  of  the  poison  are  taken  at  any  one  time. 
When  an  animal  is  finally  locoed  it  may  be  assumed  that  there  is 
very  little  of  the  poison  in  its  system  in  a  form  to  be  reached  by  an 
antidote.  While  doubtless  an  antidote  for  the  poison  may  be  found, 
it  is  not  practicable  to  use  the  antidote  as  a  remedy  for  chronic  cases. 
In  cases  of  acute  poisoning  an  antidote  can  be  used,  but  in  the  slow 
chronic  cases  it  would  be  useless  to  attempt  any  such  thing.  It 
would  seem  possible,  however,  by  the  use  of  an  antidote  to  prevent 
the  original  effects  of  the  poison.  Naturally  the  question  arises  as 
to  whether  it  may  not  be  possible  to  immunize  the  animals  by  small 
doses.  From  what  has  just  been  said  it  is  evident  that  this  is  impos- 
sible in  a  poison  of  this  character. 

In  the  way  of  remedies,  from  a  medical  standpoint,  there  would 
seem  to  be  three  things  to  be  attempted:  First,  to  give  something 


SUMMARY   OF   REMEDIES   USED.  109 

that  would  destroy  the  appetite  for  loco;  second,  to  give  an  antidote 
to  counteract  the  effects  of  the  poison;  and,  third,  to  give  such  rem- 
edies as  would  counteract  the  general  effect  of  the  poison  and  aid  the 
animal  in  recovery.  The  chances  of  finding  a  substance  that  in  one 
or  a  few  doses  would  destroy  the  appetite  for  loco  are  not  very  great. 
Some  attempts  were  made  in  this  line,  but,  as  perhaps  might  have 
been  expected,  were  unsuccessful.  Doctor  Crawford's  report  on  the 
finding  of  barium  in  the  plants  was  made  so  late  that  no  experimen- 
tation in  regard  to  an  antidote  for  this  substance  was  possible,  and 
this  part  of  the  work  will  have  to  be  taken  up  later. 

It  seemed  more  hopeful  to  make  the  attempt  to  give  remedies  for 
the  general  condition  of  the  animals  with  the  hope  of  aiding  them  in 
building  up  against  the  effects  of  the  poison.  As  has  been  indicated 
in  the  diagnosis,  the  chief  effect  of  the  poison  is  on  the  central  nerv- 
ous system,  and  this  results  not  only  in  the  marked  nervous  phe- 
nomena, but  in  anemia  and  general  debility.  In  seeking  a  remedy, 
then,  it  seemed  desirable  not  to  attempt  to  use  an  antidote  for  the 
poison,  but  to  use  such  remedies  as  would  affect  the  nervous  system 
and  aid  the  animal  in  getting  out  of  the  anemic  condition  which  is 
so  pronounced.  All  the  remedies  tried  had  this  end  in  view — to  build 
up  the  patient  with  especial  reference  to  the  nervous  system. 

Some  attempts  at  remedial  measures  were  made  in  1906.  In  the 
summer  of  1907  this  work  was  prosecuted  more  vigorously  on  the 
lines  which  were  indicated  by  the  results  of  the  previous  summer. 
Inasmuch  as  most  chronic  cases  of  loco  are  constipated,  in  all  of  the 
treatment  we  made  sure  that  there  was  free  action  of  the  bowels. 
This  was  secured  by  occasional  doses  of  Epsom  salts,  the  condition  of 
the  animals  being  watched  from  day  to  day.  During  the  summer  of 
1907  especial  attention,  too,  was  paid  to  the  diet.  All  animals  under 
treatment  were  fed  a  little  grain  daily.  With  this  was  mixed  a  little 
oil  meal  because  of  its  laxative  properties.  When  it  was  necessary 
to  feed  hay,  alfalfa  was  used,  largely  because  it  also  is  laxative. 

The  remedies  experimented  with  in  1906  were  strychnin,  potas- 
sium iodid,  asafetida,  caffein,  arsenious  acid,  Fowler's  solution,  and 
valerian.  As  the  result  of  this  work  wo  felt  convinced  that  asafetida, 
valerian,  caffein,  and  potassium  iodid  gave  no  good  effects.  In  tho 
use  of  strychnin  the  results  were  a  little  doubtful.  Two  of  tho  cattle 
were  cured  during  the  strychnin  treatment  and  there  seemed  no  good 
reason  why  this  drug  should  not  have  the  credit  of  tho  euro,  but  it 
was  true  that  other  animals  treated  with  strychnin  died,  in  somo 
cases  partly  at  least  as  the*  result  of  tho  poison.  Xono  of  tho  horses 
showed  improvement  from  tho  use  of  strychnin.  Tho  fact  that  sev- 
eral of  tho  animals  showed  indications  of  poisoning  mado  it  prolmhlo 
that  strychnin  was  administered  in  too  largo  doses,  although  only 
tho  minimum  doses  of  tho  ordinary  veterinary  matoria  modica  woro 
used.  It  seemed  probable  that  locoed  animals  woro,  perhaps,  more 


110  THE   LOCO- WEED   DISEASE   OF   THE  PLAINS. 

sensitive  to  the  effects  of  strychnin  and  should  be  treated  in  espe- 
cially small  doses. 

Arsenious  acid  effected  a  cure  in  one  of  the  horses.  This  animal 
was  treated  at  the  Colorado  Agricultural  Experiment  Station  during 
the  winter  of  1906-7  under  the  general  direction  of  Doctor  Glover, 
and,  while  it  was  a  clear-cut  case  of  loco  disease  in  the  fall  of  1906, 
with  all  the  typical  symptoms,  it  came  out  in  the  spring  definitely 
and  apparently  permanently  cured.  This  animal  was  used  as  a  sad- 
dle horse  during  the  summer  of  1907  and  at  no  time  showed  any  of 
the  signs  of  loco  poison,  if  we  except  a  slight  loss  of  spirits. 

One  of  the  cattle,  too,  after  it  was  treated  with  Fowler's  solution 
was  completely  cured. 

TREATMENT   OF    CATTLE    IN    1907. 

Fowler's  solution. — Only  one  animal  was  treated  with  Fowler's  solu- 
tion in  1907.  This  steer  was  cured,  but  the  cure  was  much  slower 
than  in  some  of  the  other  remedies,  although  the  subject  was  a  fav- 
orable one. 

Atoxyl. — One  steer  was  treated  with  atoxyl  and  recovered.  Two 
others  did  not  do  well  and  were  afterwards  put  on  strychnin  and 
improved.  The  results  from  the  use  of  atoxyl  were  not  considered 
favorable. 

Sodium  cacodylate. — Five  cattle  were  treated  with  sodium  cacody- 
late.  Of  these  1  died,  1  improved,  and  3  were  cured.  The  one  that 
died  was  an  especially  bad  case  and  nearly  hopeless  from  the  start. 
The  net  result  from  the  use  of  sodium  cacodylate  was  very  favorable. 

Strychnin. — Fourteen  head  of  locoed  cattle  were  treated  with 
strychnin.  Two  of  these  were  of  the  experiment  stock,  while  the 
others  were  brought  in  from  ranches  in  the  neighborhood  for  treat- 
ment. Of  these  14,  2  showed  improvement,  3  died,  and  9  were  cured. 
Of  those  that  died  one  was  very  much  improved  so  far  as  the  loco 
poison  was  concerned,  but  died  of  pericarditis.  The  other  two  were 
very  bad  cases  and  one  of  them  died  by  drowning,  being  too  weak  to 
get  up  after  falling  with  its  nose  under  water.  One  was  treated  with 
strychnin  followed  by  sodium  cacodylate,  followed  by  another  course 
of  strychnin,  being  treated  in  all  fifty-one  days,  and  was  discharged 
cured. 

Strychnin  and  sodium  cacodylate. — Two  were  treated  with  strychnin 
and  sodium  cacodylate  at  the  same  time  and  were  cured. 

TREATMENT    OF    HORSES  *IN    1907. 

.  Seven  horses  and  1  mule  were  under  treatment  in  1907.  In  all 
these  cases  Fowler's  solution  was  used,  but  one  was  also  treated  with 
strychnin  and  sodium  cacodylate.  No  good  results  appeared  from 
the  use  of  the  strychnin  and  sodium  cacodylate.  The  mule  died.  It 


GENERAL   RESULTS   OF   TREATMENT.  Ill 

was  an  old  animal  and  a  chronic  loco,  and  the  combination  of  troubles 
carried  it  off  in  spite  of  treatment.  Old  age  without  any  doubt  was 
an  important  factor  hi  causing  its  death.  Two  of  the  others  were  not 
treated  long  enough  for  final  results,  but  gave  promise  of  recovery. 
Two  showed  distinct  gain,  but  were  not  considered  as  positively  cured. 
Two  were  distinctly  cured. 

GENERAL    RESULTS    OF   TREATMENT. 
RESULTS   WITH   CATTLE. 

A  careful  study  of  the  cases  of  cattle  which  were  treated  in  the  two 
summers  leads  to  these  conclusions: 

1.  Very  advanced  cases  are  generally  hopeless;  occasionally  they 
may  be  cured,  but  ordinarily  they  will  die. 

2.  Cattle  may  recover  without  any  treatment  if  they  are  taken  from 
loco  and  put  upon  good  feed.     There  was  one  marked  case  of  this  kind 
in  our  herd  hi  the  summer  of  1907. 

3.  Atoxyl  is  not  effective  as  a  remedy. 

4.  Fowler's  solution  is  of  doubtful  efficacy. 

5.  Good  results  almost  invariably  follow  the  use  of  sodium  cacody- 
late  or  strychnin,  or  the  two  used  together.     We  felt  the  most  certain 
of  good  results  under  the  strychnin  treatment.     This  opinion  was 
reached  partly  as  the  result  of  a  statistical  study  of  the  cases  and 
partly  as  the  result  of  the  general  impression  made  upon  us  in  the 
course  of  treatment.     Whenever,  during  the  summer,  we  were  par- 
ticularly anxious  that  a  given  animal  should  recover,  our  tendency 
was  always  to  put  it  upon  the  strychnin  treatment. 


RESULTS    WITH    HORSES. 


The  net  result  of  the  work  of  the  two  summers  on  horses  shows: 

1.  As  in  cattle,  advanced  cases  are  hopeless. 

2.  As  hi  cattle,  recovery  is  possible  in  mild  cases  without  treatment. 

3.  Strychnin  does  not  give  good  results. 

4.  Fowler's  solution  can  be  used  with  the  expectation  of  beneficial 
results. 

PERMANENCY    OF    LOCO    CURES. 

It  must  not  be  supposed  that  an  animal  cured  of  loco  will  never  eat 
the  weed  again.  Probably  in  most  cases  if  they  have  an  opportunity 
they  will  go  back  to  their  old  habits.  When  a  horse  has  been  cured  it 
should  be  kept  in  a  pasture  free  from  loco.  When  a  steer  has  been 
cured,  it  is  probably  best  to  put  him  upon  the  market  as  soon  as  he 
is  in  sufficiently  good  flesh  rather  than  to  run  any  rusk  of  a  second 
I>eriod  of  loco  poisoning.  It  is  rather  interesting  in  this  connection, 
however,  that  the  two  head  of  cattle  which  were  cured  in  1006  and 
were  pastured  on  loco  in  1907  continued  in  the  loco  pasture  the  whole 


112  THE   LOCO- WEED   DISEASE   OF   THE  PLAINS. 

season,  eating  more  or  less  of  the  weed,  probably  rather  less,  and 
showed  little  effect.  It  seems  rather  probable  than  in  many  of  the 
cured  cases  they  are  not  as  likely  to  go  back  to  eating  loco  as  are 
animals  that  have  never  been  subjected  to  its  temptations  before. 

PREVENTION    OF    LOCO    POISONING. 

Not  all  animals  will  contract  the  loco  habit,  and  those  that  do  so 
will  ordinarily  commence  the  eating  at  a  time  when  feed  is  short.  It 
is  a  matter  of  common  knowledge  among  stockmen  that  it  is  during 
the  winter  and  spring  seasons  that  animals  are  most  likely  to  com- 
mence eating  the  loco  weeds.  This  is  especially  noticeable  in  the 
spring,  when  the  grass  of  the  preceding  season  has  been  largely  grazed 
off  and  the  new  grass  has  not  started.  At  this  time  the  loco  weeds 
are,  in  ordinary  seasons,  green  and  attractive,  and  are  frequently 
the  most  prominent  plants  in  the  plains  vegetation.  Thus  many  ani- 
mals, forced  by  hunger,  commence  to  eat  the  weeds,  and  while  some 
of  them  abandon  the  loco  after  the  grass  starts,  others  contract  the 
habit,  which  continues  even  after  there  is  an  abundance  of  good  feed, 
and  leads  eventually  to  their  death. 

Much  can  be  accomplished  by  the  stockmen  at  this  season  in  the 
way  of  prevention.  In  localities  where  the  loco  is  largely  confined 
to  definite  areas  of  the  range  it  is  possible  to  keep  the  animals  away 
from  the  loco  until  after  the  grass  has  started,  when  there  is  likely  to 
be  very  little  trouble.  In  some  cases  feeding  for  a  short  period  will 
bridge  over  the  dangerous  time,  and  while  it  may  seem  somewhat 
expensive  to  feed,  it  is  evidently  better  than  to  have  the  stock  die. 

SUMMARY    OF    WORK   ON    REMEDIES." 

1.  Some  locoed  animals  will  recover  if  taken  from  the  weed  and 
fed  well,  without  any  treatment. 

2.  Most  locoed  animals  will  recover  if  they  are  taken  from  loco, 
fed  carefully,  and  treated  on  the  lines  indicated  by  our  experiments. 

3.  In  all  cases  care  should  be  taken  to  relieve  constipation,  either 
through  the  character  of  the  food  or  by  the  use  of  magnesium 
sulphate. 

4.  Horses  are  best  treated  with  Fowler's  solution  in  daily  doses  of 
15  c.  c.,  continued  for  at  least  one  month. 

5.  Cattle  are  best  treated  with  daily  doses  of  strychnin,  the  doses 
not  exceeding  three-twentieths  of  a  grain,  given  hypodermic  ally,  and 
continued  for  one  or  two  months.     It  is  especially  important  that 
the  dose  should  be  small,  as  locoes  are  very  susceptible  to  the  bad 
effects  from  overdosing. 

a  Further  work  on  remedies  during  the  summer  season  of  1908  confirmed  the  con-< 
elusions  of  the  preceding  years. 


GENERAL  SUMMARY. 

For  many  years  complaints  have  been  made  of  the  losses  of  cattle, 
horses,  and  stock  in  the  semiarid  region  of  the  West  from  a  disease 
which  is  popularly  known  as  "loco,"  this  name  being  given  because 
of  the  crazy  symptoms  of  the  affected  animals.  The  disease  is  preva- 
lent from  the  Canadian  provinces  on  the  north  to  Mexico  on  the 
south,  and  the  losses  have  been  very  great;  so  great,  in  fact,  that  in 
some  sections  stockmen  have  been  thrown  into  bankruptcy,  and 
sometimes  most  of  the  animals  have  been  taken  off  the  range.  Some 
years  ago  the  State  of  Colorado  created  a  bounty  for  cut  and  dried 
loco,  but  such  a  large  amount  of  it  was  collected  and  the  bounty  pay- 
ments amounted  to  such  large  sums  that  the  law  was  repealed  for 
fear  that  the  whole  State  would  be  thrown  into  bankruptcy. 

Generally  speaking,  among  the  stockmen  of  this  region  the  cause 
of  the  loco  disease  has  been  ascribed  to  certain  leguminous  plants 
known  as  the  loco  weeds,  the  chit  f  of  these  being  Astragalus  moUissi- 
mus  and  Aragattus  lamberti.  During  the  last  quarter  of  the  nine- 
teenth century  this  subject  was  investigated  by  a  large  number  of 
people,  but  with  very  contradictory  results.  Attempts  were  made 
to  isolate  a  poison  from  the  loco  plants,  which  succeeded  apparently 
in  the  hands  of  certain  authors,  but  the  results  of  their  work  were 
not  corroborated  by  others.  Scientific  men  traveled  largely  through 
the  loco  region  to  observe  conditions,  and  autopsies  were  made  on  a 
considerable  number  of  animals.  While  it  was  evident  that  a  dis- 
ease of  some  kind  was  causing  enormous  losses  through  this  semiarid 
country,  the  general  result  of  the  investigations  of  scientific  men  was 
to  lead  them  to  be  veiy  skeptical  in  regard  to  the  supposed  poison- 
ous properties  of  the  loco  plants.  It  was  noticed  that  most  of  the 
so-called  locoed  animals  had  been  Subjected  to  an  unfavorable  envi- 
ronment, especially  in  the  way  of  feed,  and  the  consensus  of  opinion 
among  investigators  seemed  to  be  that  some  cause  for  the  disease 
must  be  sought  other  than  the  loco  plants.  Some  of  the  stockmen 
themselves  were  very  skeptical  in  regard  to  the  poisonous  properties 
of  the  plants,  and  contended  that  with  proper  feed  there  would  be  no 
such  thing  as  locoed  animals. 

Inasmuch  as   the  losses  were  so  heavy  and   the  stockmen  were 

anxious  to  have  the  subject  investigated  moro  thoroughly,  the  United 

States  Department  of  Agriculture  instituted  nn  experiment  in  the 

summer  of  1905  upon  a  larger  and  more  thorough  scale  than  had  been 

79154— Bull.  112—09 8  U3 


114  THE   LOCO- WEED    DISEASE   OF   THE   PLAINS. 

attempted  before,  hoping  to  prove  or  disprove  the  poisonous  proper- 
ties of  the  loco  weeds.  This  experiment  consisted  in  feeding  cattle 
and  horses  upon  pastures  containing  loco  weed  in  comparison  with 
others  fed  on  pastures  that  were  free  from  the  loco  weed,  as  well  as 
feeding  the  loco  plants  in  the  corrals,  and  of  making  as  extensive 
autopsies  upon  locoed  animals  as  possible. 

The  experiments  were  intended  (1)  to  prove  whether  the  loco  weeds 
would  poison  or  not,  (2)  to  demonstrate  the  symptoms  of  loco 
poisoning  and  the  pathological  lesions  accompanying  it,  and  (3)  to 
determine  whether  or  not  remedial  measures  could  be  instituted  for 
the  relief  of  the  loco-infested  area. 

The  conclusions  reached  as  the  result  of  the  work  of  three  seasons 
are  as  follows: 

1.  There  is  no  longer  any  question  in  regard  to  the  poisonous  prop- 
erties of  the  loco  plants.     It  was  clearly  demonstrated  that  animals 
eating  these  plants  would  succumb  sooner  or  later  to  their  poisonous 
action.     This  work,  too,  was  abundantly  corroborated  by  the  phar- 
macological work  of  Doctor  Crawford  in  the  laboratory  at  Washing- 
ton, by  whom  a  poison  was  separated  which  was  fatal  to  rabbits. 

2.  It  was  found  that  the  symptoms  of  the  loco  disease  were  essen- 
tially like  those  which  had  been  mentioned  by  the  majority  of  stock- 
men.    It  was  found  that  some  of  the  symptoms  were  exaggerated, 
but,   on  the  whole,   the  statements  of  the  stockmen  were  amply 
corroborated.     The  more  prominent  symptoms  are  a  staggering  and 
uncertain  gait,   caused   by   a  general   disturbance   of   the   nervous 
system,  which  leads  in  some  cases  to  an  apparent  partial  paralysis 
of  the  limbs  and  to  a  very  distinct  lack  of  muscular  coordination. 
The  animals  eating  loco  eat  more  and  more  of  it,  although  they  do 
not  in  all  cases  acquire  a  passionate  love  for  the  weed,  and  sooner 
or  later  lose  flesh  and  die  of  starvation. 

3.  In  the  post-mortem  examinations  it  was  found  that  there  were 
certain  quite  definite  lesions.     The  animals  were  strongly  anemic. 
This  anemia  was  indicated  not  only  by  paleness  of  flesh  and  actual 
loss  of  blood,  but  by  serous  deposits  in  various  parts  of  the  body. 
The  blood  was  found  to  be  poor  in  hemoglobin  and  commonly  rather 
rich  in  leucocytes.     A  diseased  condition  of  the  stomach  was  a  com- 
mon accompaniment  of  the  locoed  condition,  this  being  marked  in 
cattle  by  ulcers  in  the  fourth  stomach.     All  the  body  fluids  are 
rather  unusually  abundant,  and  this  is  particularly  true  of  the  fluid 
of  the  epidural  space  of  the  spinal  canal,  which  is  commonly  more  or 
less  organized,  so  that  the  spinal  canal  frequently  seems  to  be  filled 
with  a  jelly-like  substance.     There  is  a  hyperemic  condition  of  the 
central  nervous  system,  which  in   acute  cases  is  accompanied  by 
clots   in    the   lateral   ventricles.     In   females    diseased   ovaries    are 
common. 


GENERAL  SUMMARY.  115 

4.  The  common  loco  plants  in  Colorado  and  adjacent  territory  are 
AragaUus  lamberti  and  Astragalus  moUissimus.     Of  these  the  more 
widely  distributed  is  AragaUus  lamberti,  commonly  known  as  the 
"rattleweed"    or    "white   loco."     The    results    of    the    experiment 
showed  very  clearly  that  Astragalus  moUissimus  was  much  the  more- 
virulent  of  the  two  species  under  consideration.     This  plant  is  more 
abundant  in  the  southern  part  of  the  semiarid  region,  although  not 
confined  to  that.     In  Colorado  it  is  commonly  found  in  the  depres- 
sions and  on  adobe  soil,  while  AragaUus  lamberti  is  found  upon  the 
hillsides  and  upon  sandy  soil.     AragaUus  lamberti  is  not  only  com- 
mon on  the  plains,  but  also  extends  in  the  mountains  to  an  altitude 
of  perhaps  8,000  feet. 

5.  Horses,  cattle,  and  sheep  are  somewhat  differently  affected  by 
these  plants.     In  regions  covered  with  Astragalus  moUissimus  the 
only  common  locoed   animals  are  horses.     Horses  which  eat   this 
plant  become  poisoned  ordinarily  rather  quickly  and  may  die  in  a 
comparatively  short  time.     Both  cattle  and  horses  eat  AragaUus 
lamberti,  but  cattle,  perhaps,  rather  more  freely  than  horses,  so  that 
in  regions  where  AragaUus  lamberti  is  the  more  common  loco  plant 
the  cattle  are  much  more  commonly  affected  than  horses.     In  locali- 
ties where  Astragalus  moUissimus  is  the  only  loco  plant  locoed  cattle 
are  very  rare,  indeed.     Sheep  eat  both  species,  but  for  them  also 
AragaUus  lamberti  is  the  more  dangerous,  inasmuch  as  they  are  more 
apt  to  eat  this  plant  than  Astragalus  moUissimus. 

6.  It  was  found  that  there  is  a  great  difference  in  the  individual 
susceptibility  of  animals  to  the  loco  poison,  although  most  of  them  will 
succumb  to  the  temptation  and  perish  from  its  effects  sooner  or  later. 
In  regard  to  different  breeds  of  animals  there  is  a  distinct  differ- 
ence, although  the  observations  were  not  extensive  enough  for  any 
broad  generalizations.     Generally  speaking,  the  better-bred  animals 
are  more  likely  to  be  poisoned  than  those  that  have  become  accus- 
tomed to  the  country.     Among  sheep,  black-faces  yield  much  more 
quickly  than  Merinos.     Among  cattle,  Durhams  and  Aberdeen- Angus 
were  found  to  yield  more  quickly  than  Herefords. 

7.  In  regard  to  remedial  measures,  the  work  of  the  experiment  gives 
quite  definite  suggestions.     It  is  clear  that  where  land  is  sufficiently 
valuable  to  make  it  profitable  to  pay  for  that  amount  of  labor,  it  is 
entirely  feasible  to  cut  out  all  of  the  loco  weeds.     This  is  particularly 
easy  in  regard  to  Astragalus  inoU'mmntmt, because  it  grows  in  compara- 
tively small  patches.     Where  AragaUus  lamberti  is  abundant  the  work 
would  be  more  difficult ,  and  in  some  cases  the  land  is  hardly  worth  the 
expense  of  the  labor.     It  is  evident  that  in  the  case  of  fenced  pastures 
it  frequently  will  be  profitable  to  destroy  the  loco  weeds  in  this  way. 


116  THE   LOCO- WEED    DISEASE   OF   THE   PLAINS. 

In  the  case  of  open  range  it  is  probably  impracticable  to  arrange  any 
means  of  doing  this. 

In  many  cases  much  can  be  accomplished  by  keeping  animals  away 
from  ranges  covered  with  loco  during  the  time  when  feed  is  short, 
inasmuch  as  they  are  much  more  likely  to  contract  the  habit  when 
other  feed  is  lacking.  Sometimes  it  may  be  profitable  to  feed  for  a 
short  time,  in  order  that  the  habit  may  not  be  formed. 

It  is  absolutely  necessary  that  animals  which  have  acquired  a  taste 
for  loco  should  be  removed  from  temptation. 

Except  in  very  advanced  cases,  the  treatment  of  locoed  animals  can 
be  undertaken  with  every  reason  to  expect  good  results.  The  first 
essential,  of  course,  is  to  remove  to  a  pasture  which  is  free  from  loco. 
Their  feed  should  be  so  regulated  as  to  produce  looseness  of  the  bow- 
els, or  if  this  can  not  be  done  they  can  be  dosed  with  some  laxative, 
such  as  magnesium  sulphate.  Green  alfalfa  is  one  of  the  best  feeds. 
If  the  animals  are  being  fed  on  grain,  it  is  well  to  mix  oil  meal  with  the 
grain.  The  necessity  of  producing  a  loose  condition  of  the  bowels  can 
not  be  too  strongly  emphasized. 

Some  animals  will  recover  under  this  treatment  without  recourse 
to  medicine.  With  most  animals,  however,  recovery  is  hastened  by 
the  administration  of  strychnin  or  sodium  cacodylate,  or  both,  in 
the  case  of  cattle,  and  of  Fowler's  solution  in  the  case  of  horses.  All 
these  medicines  should  be  given  in  small  doses  and  continued  for  a 
considerable  period  of  time,  seldom  less  than  thirty  days.  The  daily 
doses  of  strychnin  should  not  exceed  three-twentieths  or  four- 
twentieths  of  a  grain  (or  0.009  to  0.012  gram).  Sodium  cacodylate 
should  be  given  in  daily  doses  of  6.2  grains  (or  0.4  gram).  The 
strychnin  and  sodium  cacodylate  are  best  given  by  hypodermic  injec- 
tion. Fowler's  solution  should  be  given  in  doses  of  15  to  20  c.  c.  in 
the  grain  or  in  the  drinking  water. 

Recovery  will  in  most  cases  be  slow,  as  should  be  expected  from 
the  slow  incipience  of  the  disease ;  but  care  will  bring  the  animal  to  a 
practical  cure  in  the  majority  of  cases.  Cured  animals  do  not  seem 
as  likely  to  eat  the  loco  again,  but  it  is  best  not  to  subject  them  to 
temptation. 


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INDEX. 


Page. 

Abortion  produced  by  loco 21,25,61,94 

Age  susceptibility 102 

Antelopes  poisoned  by  loco 24, 104 

Aragallus  albiflorus,  synonym  of  Aragallus  lamberti 38 

Aragallus  lamberti — 

Description,  distribution 37 

Experimental  feeding 47-68 

Less  poisonous  than  Astragalus  mollissimus 101 

Aragallus  sericeus,  synonym  of  Aragallus  lamberti 38 

Aragallus  spicatus 30, 38 

Aragallus  splendens 30 

Arizona,  loco  poisoning  in 40 

Arsenic,  treatment  with,  in  1906 78 

Astragalus  arrectus 32 

Astragalus  bisulcatus 25 

Astragalus  caryocarpus 17 

Astragalus  crotalariac 17, 18 

Astragalus  dorycnioides 28 

Astragalus  haydeniensis 25 

Astragalus  hornii 16, 1 7 

Astragalus  lagopus 28 

Astragalus  lentiginosus • 16.  18 

Astragalus  lentiginosus  var.  fremonti 17 

Astragalus  loliflorus 25 

Astragalus  menzifsii 16 

Astragalus  mollissimus — 

Description 38 

Distribution 39 

Experimental  feeding 45, 47, 48,  50,  51,  (52 

More  poisonous  than  Aragallus  lamberti 101 

Astragalus  mortoni 17 

Astragalus  oocarpa 17 

Astragalus  palousensis 28 

Astragalus  purshii 32 

Astragalus  reventus 32 

Astragalus  sftaldingii     .  2S.  32 

Astragalus  spicatus * 28,  29 

Astragalus  splendni* 2X,  29 

Atoxyl,  experiment**  with S3 

Bibliography 117 

Bif»on,  distribution  of  lorn  WM-dn  by 40 

Black-face  sheep  more  easily  affected  than  merinoe 102 

127 


128  INDEX. 

Page. 

Blood,  examination  of,  in  locoed  animals 95 

Breeds  of  animals,  different,  effect  of  loco  on 102 

Cattle- 
Experimental  feeding  of 47, 56,  71 

Experiments  with  remedies  in  1907 83 

Summary  of  treatment  of,  in  1907 110 

Cause  of  loco  disease 91 

Cleonus  quadrilineata 107 

Conclusions  derived  from  literature 34 

Cycles,  loco  growth  in 107 

Cysticercus  tenuicollis 31 

Darling  pea,  poisonous  to  stock 41 

Distribution  of  Aragallus  lamberti  and  Astragalus  mollissimus 37 

Dry  seasons,  effect  of,  on  loco 108 

Durham  cattle  more  easily  affected  than  Herefords 102 

Emmenagogue,  loco  as  an 21 

Euxesta  notata 106 

Experimental  work,  scope  and  details 42 

Experiments  at  Woodland  Park,  Colo 71 

Experiments  with  cattle — 

First  season 47 

Second  and  third  seasons 56 

At  Woodland  Park,  Colo 71 

Experiments  with  horses — 

First  season 49 

Second  and  third  seasons 62 

At  Woodland  Park,  Colo 71 

Experiments  with  sheep 66 

Extermination  of  loco  weeds 30, 105 

Fertile  soil,  relation  to  loco  plants 40 

Fowler's  solution,  experiments  with 83 

Goat,  locoed 53 

Gompholobium,  loco  weed  in  Australia 24 

Hasmonchus  metastrongylus 31 

Hemolymph  glands  in  locoed  animals 97 

Hereford  cattle  less  affected  than  other  breeds 102 

Historical  summary  of  loco  disease 15 

Horses — 

Experimental  feeding  of 49,  62,  71 

Experiments  with  remedies  in  1907 88 

Summary  of  treatment  of,  in  1907 J10 

Imperial,  Nebr.,  experiment  at 73 

Indigo — 

Disease 28 

Plant 41 

Insects  destroying  loco  plants 106 

Lambs  peculiarly  susceptible  to  loco  poisoning 95 

Lesions,  pathological,  of  loco  victims 95 

Leucocrinum  montanum 22 

Literature  of  loco  disease — 

Conclusions  from 34 

Summary  and  review . 15 

Loco  cures,  permanency  of ...,.., , , .  r . .  Ill 


INDEX.  129 

Page. 

Loco,  origin  of  name 15 

Loco  plants,  list  of 36 

Loco  poison — 

Amount  necessary  to  poison 100 

Effect  on  man 104 

Prevention  of 112 

Susceptibility  of  different  breeds  of  animals 1C2 

Time  before  symptoms  appear 1,8 

Virulence 98 

Loco  weeds,  destruction  of 105 

Lasses  from  loco  poisoning 104 

Malvastrum  coccintum 24 

Man — 

Alleged  poisoning  by  loco 25 

Susceptibility  to  loco  poisoning 104 

Merino  sheep  less  affected  than  black  faces 102 

Mule,  experimental  feeding  of 64 

Mules,  susceptibility  to  loco  poisoning 103 

"  Nenta  disease  "  of  South  Africa 29,  41 

Nervous  system  in  locoed  animals 97 

New  Mexico,  loco  poisoning  in 40 

Northwest  Territories,  loco  in 28,  29,  31 

(Estrus  ovis  in  sheep,  symptoms  like  loco 66,  68,  69,  70 

Ovaries,  diseased,  in  locoed  animals 98 

Oxytropix  lamberti 16,  1 7,  18,  19,  21,  22,  23,  24,  25.  28. 29 

Pastures  used  in  experimental  work,  description  of 44 

Pathological  lesions  of  locoed  animals 95 

Pea-eating  disease 29 

Permanency  of  loco  cures Ill 

I'hysostigma  renenosum 'J4 

Plants  known  as  loco  plants 36 

Prevention  of  loco  poisoning , . . . .  112 

Problem  of  loco  poisoning,  statement  of 42 

Rattlesnake  weed 28 

Remedies — 

Discussion 73,  108 

Experiments  with  catt  le  in  1907 S3 

General  summary 112 

Proposed  in  literature 32 

Results  in  190(5 SI 

Result*  and  conclusions  from  experiments. .  91 

Review  of  literature 15 

Sagebrush,  poisoning  by 11 

Sarrr>rystix  tetirlla :  i  1 

Sheep— 

Experiment*  and  discussion (>»>,  »•!> 

Experiment*  with  remedies  in  1907 90 

SfKliurn  cacixlylate,  ex{>eriment*  with s;{ 

Boil,  relation  of  loco  plants  to to 

Snphnra  nrrirra Hi 

Spinal  column,  wmu*  exudutc 

Stijm  viriduln 

79164-  -Hull.  112—09 9 


130  INDEX. 

Page. 

Stomach,  diseased  condition  of,  in  locoed  animals 23, 97 

Strychnin-- 
Experiments with  cattle  in  1907 86 

Treatment  with,  in  1906 75 

Summary — 

General 113 

Of  first  season's  work 54 

Susceptibility  of  different  breeds  of  animals  to  loco  poison 102 

Swainsona  galegifolia 41 

Symptoms — 

Of  loco  poisoning 92 

Mentioned  in  literature 32 

Temperature  of  locoed  animals •. 95 

Time  required  to  produce  loco  poisoning 98 

Thysanosoma  actinioides 31,  66 

Treatment,  general  results 81,  111 

Ulcers  in  stomach 23, 97 

Virulence  of  loco  poisoning 98 

Walshia  amorphella 106 

Woodland  Park,  Colo.,  experiment  at 71 

Zygadenus  elegans 22 


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